This section contains special considerations concerning Natural data manipulation language (DML) statements (that is, Natural native DML statements and Natural SQL DML statements), and Natural system variables when used with DB2.
It mainly consists of information also contained in the Natural basic documentation set where each Natural statement and variable is described in detail.
For an explanation of the symbols used in this section to describe the syntax of Natural statements, see Syntax Symbols in the Natural Statements documentation.
For information on logging SQL statements contained in a Natural program, refer to DBLOG Trace Screen for SQL Statements in the DBLOG Utility documentation.
This section covers the following topics:
NDB refreshes the following DB2 special registers automatically to the values, which applied to the least previous executed transaction.
CURRENT SQLID
CURRENT SCHEMA
CURRENT PATH
CURRENT PACKAGE PATH
NDB refreshes the following DB2 special registers only automatically to
the values, which applied to the least previous executed transaction, if the
parameter REFRESH=ON is set.
CURRENT PACKAGESET
CURRENT SERVER
Those special registers are refreshed regardless whether the previously executed transaction was rolled back or was committed.
All other special registers are not implicitly manipulated by NDB.
This section summarizes particular points you have to consider when using Natural data manipulation language (DML) statements with DB2. Any Natural statement not mentioned in this section can be used with DB2 without restriction.
Below is information on the following Natural DML statements:
The Natural native DML statement BACKOUT TRANSACTION undoes all
database modifications made since the beginning of the last logical
transaction. Logical transactions can start either after the beginning of a
session or after the last SYNCPOINT,
END TRANSACTION, or
BACKOUT TRANSACTION statement.
How the statement is translated and which command is actually issued depends on the TP-monitor environment:
If this command is executed within a Natural stored procedure or
Natural user-defined function (UDF), Natural for DB2 executes the underlying
rollback operation. This sets the caller into a must-rollback state. If this
command is executed within a Natural stored procedure or UDF for Natural error
processing (implicit ROLLBACK), Natural for DB2 does not execute
the underlying rollback operation, thus allowing the caller to receive the
original Natural error.
Under CICS, the BACKOUT TRANSACTION statement is
translated into an EXEC CICS ROLLBACK command.
However, in pseudo-conversational mode, only changes made to the database since
the last terminal I/O are undone. This is due to CICS-specific transaction
processing, see Natural for
DB2 under CICS.
Anmerkung:
Be aware that with terminal input in database loops, Natural
switches to conversational mode if no file server is used.
In batch mode and under TSO, the BACKOUT TRANSACTION
statement is translated into an SQL ROLLBACK
command.
Anmerkung:
If running in a DSNMTV01 environment, the BACKOUT
TRANSACTION statement is ignored if the used PSB has been generated
without the CMPAT=YES option.
Under IMS TM, the BACKOUT TRANSACTION statement is
translated into an IMS Rollback (ROLB) command.
However, only changes made to the database since the last terminal I/O are
undone. This is due to IMS TM-specific transaction processing, see
Natural for DB2 under IMS
TM.
As all cursors are closed when a logical unit of work ends, a
BACKOUT TRANSACTION statement must not be placed within a database
loop; instead, it has to be placed outside such a loop or after the outermost
loop of nested loops.
If an external program written in another standard programming language
is called from a Natural program, this external program must not contain its
own ROLLBACK command if the Natural program issues database calls, too. The
calling Natural program must issue the BACKOUT TRANSACTION
statement for the external program.
If a program tries to backout updates which have already been committed, for example by a terminal I/O, a corresponding Natural error message (NAT3711) is returned.
The Natural native DML statement DELETE is used to delete a row
from a table which has been read with a preceding
FIND,
READ, or
SELECT statement.
It corresponds to the SQL statement DELETE WHERE CURRENT OF
cursor-name, which means that only the row
which was read last can be deleted.
Example:
FIND EMPLOYEES WITH NAME = 'SMITH'
AND FIRST_NAME = 'ROGER'
DELETE
Natural would translate the above Natural statements into SQL and
assign a cursor name (for example, CURSOR1) as follows:
DECLARE CURSOR1 CURSOR FOR SELECT FROM EMPLOYEES WHERE NAME = 'SMITH' AND FIRST_NAME = 'ROGER' FOR UPDATE OF NAME DELETE FROM EMPLOYEES WHERE CURRENT OF CURSOR1
Both the SELECT and the DELETE statement
refer to the same cursor.
Natural translates a Natural native DML DELETE statement
into a Natural SQL DELETE statement in the same way it translates
a Natural native DML FIND statement into a
Natural SQL SELECT statement.
A row read with a FIND SORTED BY cannot be deleted due to
DB2 restrictions explained with the FIND statement. A row
read with a READ
LOGICAL cannot be deleted either.
If a row rolled out to the file server is to be deleted, Natural
rereads automatically the original row from the database to compare it with its
image stored in the file server. If the original row has not been modified in
the meantime, the DELETE operation is performed. With the next
terminal I/O, the transaction is terminated, and the row is deleted from the
actual database.
If the DELETE operates on a scrollable cursor, the row on
the file server is marked as DELETE hole and is deleted from the
base table.
However, if any modification is detected, the row will not be deleted and Natural issues the NAT3703 error message for non-scrollable cursors.
If the DELETE operates on a scrollable cursor, Natural for
DB2 simulates SQLCODE -224 THE RESULT TABLE DOES NOT AGREE WITH THE
BASE TABLE USING for DB2 compliance.
If the DELETE operates on a scrollable cursor and the row
has become a hole, Natural for DB2 simulates SQLCODE -222 AN UPDATE
OR DELETE OPERATION WAS ATTEMPTED AGAINST A HOLE.
Since a DELETE statement requires that Natural rereads a
single row, a unique index must be available for the respective table. All
columns which comprise the unique index must be part of the corresponding
Natural view.
The Natural native DML statement END TRANSACTION indicates the
end of a logical transaction and releases all DB2 data locked during the
transaction. All data modifications are committed and made permanent.
How the statement is translated and which command is actually issued depends on the TP-monitor environment:
If this command is executed from a Natural stored procedure or user defined function (UDF), Natural for DB2 does not execute the underlying commit operation. This allows the stored procedure or UDF to commit updates against non DB2 databases.
Under CICS, the END TRANSACTION statement is translated
into an EXEC CICS SYNCPOINT command. If the file
server is used, an implicit end-of-transaction is issued after each terminal
I/O. This is due to CICS-specific transaction processing in
pseudo-conversational mode, see Natural for DB2 under
CICS.
In batch mode and under TSO, the END TRANSACTION
statement is translated into an SQL COMMIT WORK
command.
Anmerkung:
If running in a DSNMTV01 environment the END
TRANSACTION statement is ignored if the used PSB has been generated
without the CMPAT=YES option.
Under IMS TM, the END TRANSACTION statement is not
translated into an IMS CHKP call, but is ignored. Due to IMS TM-specific
transaction processing (see Natural for DB2 under IMS
TM), an implicit end-of-transaction is issued after each
terminal I/O.
Except when used in combination with the SQL
WITH
HOLD clause (see SELECT - SQL in
Using Natural SQL
Statements), an END TRANSACTION statement
must not be placed within a database loop, since all cursors are closed when a
logical unit of work ends. Instead, it has to be placed outside such a loop or
after the outermost loop of nested loops.
If an external program written in another standard programming language
is called from a Natural program, this external program must not contain its
own COMMIT command if the Natural program issues
database calls, too. The calling Natural program must issue the END
TRANSACTION statement on behalf of the external program.
Anmerkung:
With DB2, the END TRANSACTION statement cannot be used
to store transaction data.
The Natural native DML statement FIND corresponds to the Natural
SQL statement SELECT.
Example:
Natural native DML statements:
FIND EMPLOYEES WITH NAME = 'BLACKMORE' AND AGE EQ 20 THRU 40 OBTAIN PERSONNEL_ID NAME AGE
Equivalent Natural SQL statement:
SELECT PERSONNEL_ID, NAME, AGE
FROM EMPLOYEES
WHERE NAME = 'BLACKMORE'
AND AGE BETWEEN 20 AND 40
Natural internally translates a FIND statement into an SQL
SELECT statement
as described in Processing of SQL Statements Issued
by Natural in the section
Internal Handling of Dynamic
Statements. The SELECT statement is executed
by an OPEN CURSOR statement followed by a
FETCH command. The FETCH
command is executed repeatedly until either all records have been read or the
program flow exits the FIND processing loop. A CLOSE
CURSOR command ends the SELECT processing.
The WITH clause of a
FIND statement is converted to the WHERE clause of
the SELECT statement. The basic search criterion for a DB2 table
can be specified in the same way as for an Adabas file. This implies that only
database fields which are defined as descriptors can be used to construct basic
search criteria and that descriptors cannot be compared with other fields of
the Natural view (that is, database fields) but only with program variables or
constants.
Anmerkung:
As each database field (column) of a DB2 table can be used for
searching, any database field can be defined as a descriptor in a Natural
DDM.
The WHERE clause of the
FIND statement is evaluated by Natural after the rows
have been selected via the WITH clause. Within
the WHERE clause, non-descriptors can be used and database fields
can be compared with other database fields.
Anmerkung:
DB2 does not have sub-, super-, or phonetic descriptors.
A FIND
NUMBER statement is translated into a SELECT
statement containing a COUNT(*) clause. The number of rows found
is returned in the Natural system variable
*NUMBER
as described in the Natural System Variables
documentation.
The FIND
UNIQUE statement can be used to ensure that only one record
is selected for processing. If the FIND UNIQUE statement is
referenced by an UPDATE statement, a non-cursor (Searched)
UPDATE operation is generated instead of a cursor-oriented
(Positioned)
UPDATE operation. Therefore, it can be used if you want
to update a DB2 primary key. It is, however, recommended to use the Natural SQL
Searched UPDATE statement to
update a primary key.
In static mode, the FIND NUMBER and FIND
UNIQUE statements are translated into a
SELECT
SINGLE statement as described in the section
Using Natural SQL
Statements.
The FIND
FIRST statement cannot be used. The
PASSWORD,
CIPHER,
COUPLED
and RETAIN
clauses cannot be used either.
The SORTED
BY clause of a FIND statement is translated into
the SQL SELECT
... ORDER BY clause, which follows the search criterion.
Because this produces a read-only result table, a row read with a
FIND statement that contains a SORTED BY clause
cannot be updated or deleted.
A limit on the depth of nested database loops can be specified at installation time. If this limit is exceeded, a Natural error message is returned.
Anmerkungen:
FIND (5), the limitation value will be translated
into a FETCH FIRST integer ROWS ONLY
clause in the generated SQL string.
MULTIFETCH clause
of the FIND
statement.
As far as the file server is concerned, there are no programming restrictions with selection statements. It is, however, recommended to make yourself familiar with its functionality considering performance and file server space requirements.
The Natural DML statement HISTOGRAM returns the number
of rows in a table which have the same value in a specific column. The number
of rows is returned in the Natural system variable
*NUMBER
as described in the Natural System Variables
documentation.
Example:
Natural native DML statements:
HISTOGRAM EMPLOYEES FOR AGE OBTAIN AGE
Equivalent Natural SQL statement:
SELECT COUNT(*), AGE FROM EMPLOYEES WHERE AGE > -999 GROUP BY AGE ORDER BY AGE
Natural translates the HISTOGRAM statement into an SQL
SELECT statement, which means that the control flow is similar to
the flow explained for the FIND statement.
Anmerkung:
With Universal Database Server for z/OS Version 8, Natural for DB2
supports DB2 multiple row processing on behalf of the
MULTIFETCH
clause of the HISTOGRAM statement.
The Natural native DML statement READ can also be used to access
DB2 tables. Natural translates a READ statement into an SQL
SELECT
statement.
READ
PHYSICAL and READ LOGICAL can be used;
READ BY ISN,
however, cannot be used, as there is no DB2 equivalent to Adabas ISNs. The
PASSWORD
and CIPHER
clauses cannot be used either.
Since a READ LOGICAL statement is translated into a
SELECT ... ORDER
BY statement, which produces a read-only table, a row read
with a READ LOGICAL statement cannot be updated or deleted (see
Example 1). The start value can only be a constant or a program variable; any
other field of the Natural view (that is, any database field) cannot be
used.
A READ PHYSICAL statement is translated into a
SELECT statement without an ORDER BY clause and can
therefore be updated or deleted (see Example 2).
Example 1:
Natural native DML statements:
READ PERSONNEL BY NAME OBTAIN NAME FIRSTNAME DATEOFBIRTH
Equivalent Natural SQL statement:
SELECT NAME, FIRSTNAME, DATEOFBIRTH FROM PERSONNEL
WHERE NAME >= ' '
ORDER BY NAME
Example 2:
The Natural native DML statements:
READ PERSONNEL PHYSICAL OBTAIN NAME
Equivalent Natural SQL statement:
SELECT NAME FROM PERSONNEL
If the READ statement contains a
WHERE clause,
this clause is evaluated by the Natural processor after the rows have
been selected according to the descriptor value(s) specified in the search
criterion.
If a processing limit is specified as a constant integer number, for
example, READ (5), in the SQL string generated, the value that
defines the limitation will be translated into the clause
FETCH FIRST
integer ROWS
ONLY |
Natural for DB2 uses insensitive scrollable cursors to process the
following READ
statement:
READ
.. [IN] [LOGICAL] VARIABLE/DYNAMIC
operand5 [SEQUENCE] |
Natural for DB2 uses insensitive scrollable cursors to process the
READ statement below. If relating to a
Positioned
UPDATE or
Positioned
DELETE statement, Natural for DB2 uses insensitive
static cursors.
READ .. [IN] [PHYSICAL]
DESCENDING/VARIABLE/DYNAMIC operand5
[SEQUENCE] |
operand5
Value A will be translated into a FETCH
FIRST/NEXT DB2 access, and value D into a FETCH
LAST/PRIOR DB2 access.
Anmerkung:
Natural for DB2 supports DB2 multiple row processing on behalf of
the MULTIFETCH clause of
the READ statement.
As far as the file server is concerned there are no programming restrictions with selection statements. It is, however, recommended to make yourself familiar with its functionality considering performance and file server space requirements.
The Natural native DML statement STORE is used to add a row to a
DB2 table. The STORE statement corresponds to the SQL statement
INSERT.
Example:
The Natural native DML statement:
STORE RECORD IN EMPLOYEES
WITH PERSONNEL_ID = '2112'
NAME = 'LIFESON'
FIRST_NAME = 'ALEX'
Equivalent Natural SQL statement:
INSERT INTO EMPLOYEES (PERSONNEL_ID, NAME, FIRST_NAME)
VALUES ('2112', 'LIFESON', 'ALEX')
The PASSWORD, CIPHER and USING/GIVING
NUMBER clauses of the STORE statement cannot be used.
The Natural native DML statement UPDATE updates a row in a DB2
table which has been read with a preceding FIND,
READ, or
SELECT statement.
It corresponds to the SQL statement UPDATE WHERE CURRENT OF
cursor-name (Positioned
UPDATE), which means that only the row which was read
last can be updated.
If a row rolled out to the file server is to be updated, Natural
automatically rereads the original row from the database to compare it with its
image stored in the file server. If the original row has not been modified in
the meantime, the UPDATE operation is performed. With the next
terminal I/O, the transaction is terminated and the row is definitely updated
on the database.
If the UPDATE operates on a scrollable cursor, the row on
the file server and the row in the base table are updated. If the row no longer
qualifies for the search criteria of the related
SELECT statement
after the update, the row is marked as UPDATE hole on the file
server.
However, if any modification is detected, the row will not be updated and Natural issues the NAT3703 error message for non-scrollable cursors.
If the UPDATE operates on a scrollable cursor, Natural
for DB2 simulates SQLCODE -224 THE RESULT TABLE DOES NOT AGREE WITH
THE BASE TABLE USING for DB2 compliance.
If the UPDATE operates on a scrollable cursor and the row
has become a hole, Natural for DB2 simulates SQLCODE -222 AN UPDATE
OR DELETE OPERATION WAS ATTEMPTED AGAINST A HOLE.
Since an UPDATE statement requires rereading a single row
by Natural, a unique index must be available for this table. All columns which
comprise the unique index must be part of the corresponding Natural view.
As explained with the Natural native DML statement
FIND, Natural
translates a FIND statement into an SQL
SELECT statement.
When a Natural program contains a DML UPDATE statement, this
statement is translated into an SQL UPDATE statement and a
FOR UPDATE OF clause is
added to the SELECT statement.
Example:
FIND EMPLOYEES WITH SALARY < 5000 ASSIGN SALARY = 6000 UPDATE
Natural would translate the above Natural statements into SQL and assign a cursor name (for example, CURSOR1) as follows:
DECLARE CURSOR1 CURSOR FOR SELECT SALARY FROM EMPLOYEES WHERE SALARY < 5000 FOR UPDATE OF SALARY UPDATE EMPLOYEES SET SALARY = 6000 WHERE CURRENT OF CURSOR1
Both the SELECT and the UPDATE statement
refer to the same cursor.
Due to DB2 logic, a column (field) can only be updated if it is
contained in the FOR UPDATE OF clause; otherwise updating this
column (field) is rejected. Natural includes automatically all columns (fields)
into the FOR UPDATE OF clause which have been modified anywhere in
the Natural program or which are input fields as part of a Natural map.
However, an DB2 column is not updated if the column (field) is marked
as "not updateable" in the Natural DDM. Such columns (fields) are
removed from the FOR UPDATE OF list without any warning or error
message. The columns (fields) contained in the FOR UPDATE OF list
can be checked with the LISTSQL
command.
The Adabas short name in the Natural DDM determines whether a column (field) can be updated.
The following table shows the ranges that apply:
| Short-Name Range | Type of Field |
|---|---|
| AA - N9 | non-key field that can be updated |
| Aa - Nz | non-key field that can be updated |
| OA - O9 | primary key field |
| PA - P9 | ascending key field that can be updated |
| QA - Q9 | descending key field that can be updated |
| RA - X9 | non-key field that cannot be updated |
| Ra - Xz | non-key field that cannot be updated |
| YA - Y9 | ascending key field that cannot be updated |
| ZA - Z9 | descending key field that cannot be updated |
| 1A - 9Z | non-key field that cannot be updated |
| 1a - 9z | non-key field that cannot be updated |
Be aware that a primary key field is never part of a FOR UPDATE
OF list. A primary key field can only be updated by using a non-cursor
UPDATE operation (see also Natural SQL
UPDATE
statement in the section Using Natural SQL Statements).
A row read with a FIND statement that contains a
SORTED
BY clause cannot be updated (due to DB2 limitations as
explained with the FIND statement). A row
read with a READ
LOGICAL statement cannot be updated either (as explained with
the READ
statement).
If a column is to be updated which is redefined as an array, it is
strongly recommended to update the whole column and not individual occurrences;
otherwise, results are not predictable. To do so, in reporting mode you can use
the OBTAIN statement,
which must be applied to all field occurrences in the column to be updated. In
structured mode, however, all these occurrences must be defined in the
corresponding Natural view.
The data locked by an UPDATE statement are released when
an END TRANSACTION
(COMMIT WORK) or BACKOUT
TRANSACTION (ROLLBACK WORK) statement is
executed by the program.
Anmerkung:
If a length indicator field or NULL indicator field
is updated in a Natural program without updating the field (column) it refers
to, the update of the column is not generated for DB2 and thus no updating
takes place.
In general, the Natural native DML statement UPDATE can
be used in both structured and reporting mode. However, after a
SELECT statement, only the syntax defined for Natural structured
mode is allowed:
UPDATE [RECORD] [IN] [STATEMENT] [(r)]
|
This is due to the fact that in combination with the
SELECT statement, the Natural native DML UPDATE
statement is only allowed in the special case of:
... SELECT ... INTO VIEW view-name ...
Thus, only a whole Natural view can be updated; individual columns (fields) cannot.
Example:
DEFINE DATA LOCAL
01 PERS VIEW OF SQL-PERSONNEL
02 NAME
02 AGE
END-DEFINE
SELECT *
INTO VIEW PERS
FROM SQL-PERSONNEL
WHERE NAME LIKE 'S%'
IF NAME = 'SMITH'
ADD 1 TO AGE
UPDATE
END-IF
END-SELECT
...
In combination with the Natural native DML UPDATE
statement, any other form of the SELECT statement is rejected and
an error message is returned.
In all other respects, the Natural native DML UPDATE
statement can be used with the SELECT statement in the same way as
with the Natural FIND statement.
This section covers points you have to consider when using Natural SQL statements with DB2. These DB2-specific points partly consist in syntax enhancements which belong to the Extended Set of Natural SQL syntax. The Extended Set is provided in addition to the Common Set to support database-specific features; see Common Set and Extended Set in the section SQL Statements in the Natural Statements documentation.
For information on logging SQL statements contained in a Natural program, refer to DBLOG Trace Screen for SQL Statements in the DBLOG Utility documentation.
Below is information on the following Natural SQL statements and on common syntactical items:
The following common syntactical items are either DB2-specific and do not conform to the standard SQL syntax definitions (that is, to the Common Set of Natural SQL syntax) or impose restrictions when used with DB2 (see also SQL Statements in the Natural Statements documentation).
Below is information on the following common syntactical items:
An atom can be either a parameter (that is, a Natural program variable or host variable) or a constant. When running dynamically, however, the use of host variables is restricted by DB2. For further details, refer to the relevant DB2 literature by IBM.
The comparison operators specific to DB2 belong to the Natural Extended Set. For a description, refer to Comparison Predicate in Search Conditions, Natural SQL Statements in the Natural Statements documentation.
The following factors are specific to DB2 and belong to the Natural SQL Extended Set:
|
special-register |
A scalar function is a built-in function that can be used in the construction of scalar computational expressions. Scalar functions are specific to DB2 and belong to the Natural SQL Extended Set.
The scalar functions Natural for DB2 supports are listed below in alphabetical order:
| A - H | I - R | S - Z |
|---|---|---|
|
|
|
|
Each scalar function is followed by one or more scalar expressions in parentheses. The number of scalar expressions depends upon the scalar function. Multiple scalar expressions must be separated from one another by commas.
Example:
SELECT NAME
INTO NAME
FROM SQL-PERSONNEL
WHERE SUBSTR ( NAME, 1, 3 ) = 'Fri'
...
A column function returns a single-value result for the argument it receives. The argument is a set of like values, such as the values of a column. Column functions are also called aggregating functions.
The following column functions conform to standard SQL. They are not specific to DB2:
AVG
COUNT
MAX
MIN
SUM
The following column functions do not conform to standard SQL. They are specific to DB2 and belong to the Natural SQL Extended Set.
COUNT_BIG
CORRELATION
COVARIANCE
COVARIANCE_SAMP
STDDEV
STDDEV_POP
STDDEV_SAMP
VAR
VAR_POP
VAR_SAMP
VARIANCE
VARIANCE_SAMP
XMLAGG
The concatenation operator (CONCAT or ||)
does not conform to standard SQL. It is specific to DB2 and belongs to the
Natural Extended
Set.
With the exception of USER, the following special
registers do not conform to standard SQL. They are specific to DB2 and belong
to the Natural SQL Extended
Set:
CURRENT APPLICATION ENCODING SCHEME
CURRENT CLIENT_ACCNTG
CURRENT CLIENT_APPLNAME
CURRENT CLIENT_USERID
CURRENT CLIENT_WRKSTNNAME
CURRENT DATE
CURRENT_DATE
CURRENT DEBUG MODE
CURRENT DECFLOAT ROUNDING MODE
CURRENT DEGREE
CURRENT FUNCTION PATH
CURRENT_LC_CTYPE
CURRENT LC_CTYPE
CURRENT LOCALE LC_CTYPE
CURRENT MAINTAINED TABLE TYPES FOR
OPTIMIZATION
CURRENT_MEMBER
CURRENT OPTIMIZATION HINT
CURRENT PACKAGE PATH
CURRENT PACKAGESET
CURRENT_PATH
CURRENT PRECISION
CURRENT REFRESH AGE
CURRENT ROUTINE VERSION
CURRENT RULES
CURRENT SCHEMA
CURRENT SERVER
CURRENT SQLID
CURRENT TIME
CURRENT_TIME
CURRENT TIMESTAMP
CURRENT TIMEZONE
CURRENT_TIMEZONE USER
SESSION TIME ZONE
SESSION_USER
USER
A reference to a special register returns a scalar value.
Using the command SET CURRENT SQLID, the
creator name of a table can be substituted by the current SQLID. This enables
you to access identical tables with the same table name but with different
creator names.
Units, also called "durations", are specific to DB2 and belong to the Natural SQL Extended Set.
The following units are supported:
DAY
DAYS
HOUR
HOURS
MICROSECOND
MICROSECONDS
MINUTE
MINUTES
MONTH
MONTHS
SECOND
SECONDS
YEAR
YEARS
CASE
|
|
searched-when-clause ...
|
|
|
ELSE
|
|
|
|
|
END
|
Case-expressions do not
conform to standard SQL and are therefore supported by the Natural SQL
Extended Set
only.
DEFINE DATA LOCAL
01 #EMP
02 #EMPNO (A10)
02 #FIRSTNME (A15)
02 #MIDINIT (A5)
02 #LASTNAME (A15)
02 #EDLEVEL (A13)
02 #INCOME (P7)
END-DEFINE
SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME,
(CASE WHEN EDLEVEL < 15 THEN 'SECONDARY'
WHEN EDLEVEL < 19 THEN 'COLLEGE'
ELSE 'POST GRADUATE'
END ) AS EDUCATION, SALARY + COMM AS INCOME
INTO
#EMPNO, #FIRSTNME, #MIDINIT, #LASTNAME,
#EDLEVEL, #INCOME
FROM DSN8510-EMP
WHERE (CASE WHEN SALARY = 0 THEN NULL
ELSE SALARY / COMM
END ) > 0.25
DISPLAY #EMP
END-SELECT
END
The Natural SQL statement CALLDBPROC is used to call DB2
stored procedures. It supports the result set mechanism of DB2 and it enables
you to call DB2 stored procedures. For further details and statement syntax,
see CALLDBPROC
in the Natural Statements documentation.
The following topics are covered below:
If the CALLDBPROC statement is
executed dynamically, all parameters and constants are mapped to the variables
of the following DB2 SQL statement:
CALL :hv USING DESCRIPTOR :sqlda statement
:hv denotes a host variable
containing the name of the procedure to be called and
:sqlda is a dynamically generated sqlda
describing the parameters to be passed to the stored procedure.
If the CALLDBPROC statement is executed statically, the
constants of the CALLDBPROC statement are also generated as
constants in the generated assembler SQL source for the DB2 precompiler.
If the SQLCODE created by the CALL statement indicates that
there are result sets (SQLCODE +466 and +464),
Natural for DB2 runtime executes a DESCRIBE PROCEDURE
:hv INTO :sqlda
statement in order to retrieve the result set locator values of the result sets
created by the invoked stored procedure. These values are put into the
RESULT
SETS variables specified in the CALLDBPROC
statement. Each RESULT SETS variable specified in a
CALLDBPROC for which no result set locator value is present is
reset to zero. The result set locator values can be used to read the result
sets by means of the READ
RESULT SET statement as long as the database transaction
which created the result set has not yet issued a COMMIT or
ROLLBACK.
If the result set was created by a cursor
WITH
HOLD, the result set locator value remains valid after a
COMMIT operation.
Unlike other Natural SQL statements, CALLDBPROC enables
you (optionally!) to specify an SQLCODE variable following the
GIVING
keyword which will contain the SQLCODE of the underlying
CALL statement. If
GIVING is specified, it is up to the Natural program to react on
the SQLCODE (error message NAT3700 is not issued by the runtime).
Below are the parameter data types supported by the
CALLDBPROC statement:
| Natural Format/Length | DB2 Data Type |
|---|---|
| An | CHAR(n) |
| B2 | SMALLINT |
| B4 | INT |
|
Bn |
CHAR(n) |
| F4 | REAL |
| F8 | DOUBLE PRECISION |
| I2 | SMALLINT |
| I4 | INT |
| Nnn.m | NUMERIC(nn+m,m) |
| Pnn.m | NUMERIC(nn+m,n) |
| Gn | GRAPHIC(n) |
| An/1:m | VARCHAR(n*m) |
| D | DATE |
| T | TIME
Anmerkung: |
This parameter is used to invoke Natural stored procedures defined
with PARAMETER STYLE GENERAL/WITH NULL.
If the CALLMODE=NATURAL
parameter is specified, an additional parameter describing the parameters
passed to the Natural stored procedure is passed from the client, that is,
caller, to the server, that is, the Natural for DB2 server stub. The parameter
is the Stored Procedure Control Block (STCB; see also
STCB
Layout in PARAMETER
STYLE in the section Processing Natural Stored Procedures and
UDFs) and has the format VARCHAR from the
viewpoint of DB2. Therefore, every Natural stored procedure defined with
PARAMETER STYLE GENERAL/WITH NULL has to be defined with the
CREATE PROCEDURE statement by using this VARCHAR
parameter as the first in its PARMLIST row.
From the viewpoint of the caller, that is, the Natural program, and
from the viewpoint of the stored procedure, that is, Natural subprogram, the
STCB is invisible. It is passed as first parameter by the Natural for DB2
runtime and it is used as on the server side to build the copy of the passed
data in the Natural thread and the corresponding
CALLNAT statement.
Additionally, this parameter serves as a container for error information
created during execution of the Natural stored procedure by the Natural
runtime. It also contains information on the library where you are logged on
and the Natural subprogram to be invoked.
Below is a sample program for issuing
CALLDBPROC and
READ RESULT
SET statements:
DEFINE DATA LOCAL
1 ALPHA (A8)
1 NUMERIC (N7.3)
1 PACKED (P9.4)
1 VCHAR (A20/1:5) INIT <'DB25SGCP'>
1 INTEGER2 (I2)
1 INTEGER4 (I4)
1 BINARY2 (B2)
1 BINARY4 (B4)
1 BINARY12 (B12)
1 FLOAT4 (F4)
1 FLOAT8 (F8)
1 INDEX-ARRAY (I2/1:11)
1 INDEX-ARRAY1(I2)
1 INDEX-ARRAY2(I2)
1 INDEX-ARRAY3(I2)
1 INDEX-ARRAY4(I2)
1 INDEX-ARRAY5(I2)
1 INDEX-ARRAY6(I2)
1 INDEX-ARRAY7(I2)
1 INDEX-ARRAY8(I2)
1 INDEX-ARRAY9(I2)
1 INDEX-ARRAY10(I2)
1 INDEX-ARRAY11(I2)
1 #RESP (I4)
1 #RS1 (I4) INIT <99>
1 #RS2 (I4) INIT <99>
LOCAL
1 V1 VIEW OF SYSIBM-SYSTABLES
2 NAME
1 V2 VIEW OF SYSIBM-SYSPROCEDURES
2 PROCEDURE
2 RESULT_SETS
1 V (I2) INIT <99>
END-DEFINE
CALLDBPROC 'DAEFDB25.SYSPROC.SNGSTPC' DSN8510-EMP
ALPHA INDICATOR :INDEX-ARRAY1
NUMERIC INDICATOR :INDEX-ARRAY2
PACKED INDICATOR :INDEX-ARRAY3
VCHAR(*) INDICATOR :INDEX-ARRAY4
INTEGER2 INDICATOR :INDEX-ARRAY5
INTEGER4 INDICATOR :INDEX-ARRAY6
BINARY2 INDICATOR :INDEX-ARRAY7
BINARY4 INDICATOR :INDEX-ARRAY8
BINARY12 INDICATOR :INDEX-ARRAY9
FLOAT4 INDICATOR :INDEX-ARRAY10
FLOAT8 INDICATOR :INDEX-ARRAY11
RESULT SETS #RS1 #RS2
CALLMODE=NATURAL
READ (10) RESULT SET #RS2 INTO VIEW V2 FROM SYSIBM-SYSTABLES
WRITE 'PROC F RS :' PROCEDURE 50T RESULT_SETS
END-RESULT
END
The Natural SQL COMMIT statement indicates the end of a
logical transaction and releases all DB2 data locked during the transaction.
All data modifications are made permanent. For further details and statement
syntax, see COMMIT -
SQL in the Natural Statements
documentation.
COMMIT is a synonym for the Natural native DML statement
END
TRANSACTION as described in the section
Using Natural Native DML
Statements.
No transaction data can be provided with the COMMIT
statement.
If this command is executed from a Natural stored procedure or user-defined function (UDF), Natural for DB2 does not execute the underlying commit operation. This allows the Natural stored procedure or UDF to commit updates against non DB2 databases.
Under CICS, the COMMIT statement is translated into an
EXEC CICS SYNCPOINT command. If the file server is
used, an implicit end-of-transaction is issued after each terminal I/O. This is
due to CICS-specific transaction processing in pseudo-conversational mode, see
Natural for DB2 under
CICS.
Under IMS TM, the COMMIT statement is not translated into
an IMS CHECKPOINT command, but is ignored. An
implicit end-of-transaction is issued after each terminal I/O. This is due to
IMS TM-specific transaction processing, see
Natural for DB2 under IMS
TM.
Unless when used in combination with the
WITH
HOLD clause (see
SELECT
- Cursor-Oriented in the Natural
Statements documentation), a COMMIT statement
must not be placed within a database loop, since all cursors are closed when a
logical unit of work ends. Instead, it has to be placed outside such a loop or
after the outermost loop of nested loops.
If an external program written in another standard programming language
is called from a Natural program, this external program must not contain its
own COMMIT command if the Natural program issues database calls,
too. The calling Natural program must issue the COMMIT statement
on behalf of the external program.
Both the cursor-oriented or
Positioned
DELETE, and the non-cursor or
Searched
DELETE statements are supported as part of Natural SQL;
the functionality of the
Positioned
DELETE statement corresponds to that of the Natural DML
DELETE
statement. For further details and statement syntax, see
DELETE in the
Natural Statements documentation.
With DB2, a table name in the
FROM
Clause of a
Searched
DELETE statement can be assigned a
correlation-name.
This does not correspond to the standard SQL syntax definition and therefore
belongs to the Natural SQL Extended Set.
The Searched DELETE statement must be used, for example,
to delete a row from a self-referencing table, since with self-referencing
tables a Positioned DELETE is not allowed by DB2.
The Natural SQL INSERT statement is used to add one or
more new rows to a table.
Since the INSERT statement can contain a select
expression, all the DB2-specific common syntactical items described
above apply.
For further details and statement syntax, see
INSERT in the
Natural Statements documentation.
The MERGE statement is a hybrid SQL statement consisting
of an UPDATE component and an INSERT component. It
allows you either to insert a row into a DB2 table or to update a row of a DB2
table if the input data matches an already existing row of a table.
The MERGE statement belongs to the SQL Extended Set.
For further details and statement syntax, see
MERGE in the
Natural Statements documentation.
The Natural PROCESS SQL statement is used to issue SQL
statements to the underlying database. The statements are specified in a
statement-string, which can also
include constants and parameters. The set of statements which can be issued is
also referred to as Flexible SQL and comprises those statements which can be
issued with the SQL statement EXECUTE.
In addition, Flexible SQL includes the following DB2-specific statements:
CALL
CONNECT
GET DIAGNOSTICS
SET APPLICATION ENCODING SCHEME
SET CONNECTION
SET CURRENT DEGREE
SET CURRENT LC_CTYPE
SET CURRENT OPTIMIZATION HINT
SET CURRENT MAINTAINED TABLE TYPES FOR
OPTIMIZATION
SET CURRENT PACKAGE PATH
SET CURRENT PACKAGESET
SET CURRENT PATH
SET CURRENT PRECISION
SET CURRENT REFRESH AGE
SET CURRENT RULES
SET CURRENT SCHEMA
SET CURRENT SQLID
SET ENCRYPTION PASSWORD
SET
host-variable=special-register
RELEASE
Anmerkungen:
PROCESS SQL are skipped
during static generation. Thus they are always executed dynamically via
NDBIOMO.
COMMIT and
ROLLBACK
statements must not be used within PROCESS SQL.
For further details and statement syntax, see
PROCESS SQL in
the Natural Statements documentation.
The Natural SQL READ RESULT SET statement reads a result
set created by a Natural stored procedure that was invoked by a
CALLDBPROC
statement. For details on how to specify the scroll direction by using the
variable scroll-hv, see
the SELECT
statement.
For further details and statement syntax, see
READ RESULT
SET in the Natural Statements
documentation.
The Natural SQL ROLLBACK statement undoes
all database modifications made since the beginning of the last logical
transaction. Logical transactions can start either after the beginning of a
session or after the last COMMIT/END TRANSACTION or
ROLLBACK/BACKOUT TRANSACTION statement. All records
held during the transaction are released.
For further details and statement syntax, see
ROLLBACK -SQL in
the Natural Statements documentation.
ROLLBACK is a synonym for the Natural statement
BACKOUT
TRANSACTION as described in the section
Using Natural Native DML
Statements.
If this command is executed from a Natural stored procedure or
user-defined function (UDF), Natural for DB2 executes the underlying rollback
operation. This sets the caller into a must-rollback state. If this command is
executed by Natural error processing (implicit ROLLBACK), Natural
for DB2 does not execute the underlying rollback operation, thus allowing the
caller to receive the original Natural error.
Under CICS, the ROLLBACK statement is translated into an
EXEC CICS ROLLBACK command. However, if the file
server is used, only changes made to the database since the last terminal I/O
are undone. This is due to CICS-specific transaction processing in
pseudo-conversational mode, see Natural for DB2 under
CICS.
Under IMS TM, the ROLLBACK statement is translated into an
IMS Rollback (ROLB) command. However, only changes
made to the database since the last terminal I/O are undone. This is due to IMS
TM-specific transaction processing, see
Natural for DB2 under IMS
TM.
As all cursors are closed when a logical unit of work ends, a
ROLLBACK statement must not be placed within a database loop;
instead, it has to be placed outside such a loop or after the outermost loop of
nested loops.
If an external program written in another standard programming language
is called from a Natural program, this external program must not contain its
own ROLLBACK command if the Natural program issues database calls,
too. The calling Natural program must issue the ROLLBACK statement
on behalf of the external program.
The Natural SQL SELECT statement supports both the
cursor-oriented selection, which is used to retrieve an arbitrary number of
rows and the non-cursor selection (Singleton SELECT), which
retrieves at most one single row.
For full details and statement syntax, see
SELECT -SQL in the
Natural Statements documentation.
Like the Natural native DML FIND statement, the
cursor-oriented SELECT statement is used to select a set of rows
(records) from one or more DB2 tables, based on a search criterion. Since a
database loop is initiated, the loop must be closed by a LOOP
statement (in reporting mode) or by an END-SELECT statement (in
structured mode). With this construction, Natural uses the same loop processing
as with the FIND statement. In addition, no cursor management is
required from the application program; it is automatically handled by Natural.
For further details and syntax, see SELECT - SQL, Syntax 1 - Cursor-Oriented Selection in the Natural Statements documentation.
The Natural SQL statement SELECT SINGLE provides the
functionality of a non-cursor selection (Singleton SELECT); that
is, a select expression that retrieves at most one row without using a
cursor.
Since DB2 supports the Singleton SELECT command in static
SQL only, in dynamic mode, the Natural SELECT SINGLE statement is
executed in the same way as a set-level SELECT statement, which
results in a cursor operation. However, Natural checks the number of rows
returned by DB2. If more than one row is selected, a corresponding error
message is returned.
For further details and syntax, see SELECT - SQL, Syntax 2 - Non-Cursor Selection in the Natural Statements documentation.
Both the cursor-oriented or
Positioned
UPDATE and the non-cursor or
Searched
UPDATE statements are supported as part of Natural SQL.
Both of them reference either a table or a Natural view.
With DB2, the name of a table or Natural view to be referenced by a
Searched UPDATE can be assigned a
correlation-name.
This does not correspond to the standard SQL syntax definition and therefore
belongs to the Natural Extended Set.
The Searched UPDATE statement must be used, for example,
to update a primary key field, since DB2 does not allow updating of columns of
a primary key by using a Positioned UPDATE statement.
Anmerkung:
If you use the SET * notation, all fields of the
referenced Natural view are added to the FOR UPDATE OF and
SET lists. Therefore, ensure that your view contains only fields
which can be updated; otherwise, a negative SQLCODE is returned by DB2.
For further details and syntax, see UPDATE - SQL in the Natural Statements documentation.
When used with DB2, there are restrictions and/or special considerations concerning the following Natural system variables:
For information on restrictions and/or special considerations, refer to the section Database-Specific Information in the corresponding system variable documentation.
This section describes the multiple row functionality for DB2 databases.
You have to operate against DB2 for z/OS Version 8 or higher to use these features.
Natural for DB2 provides two kinds of multiple row processing features:
This feature does not influence the program logic. Although the Natural native DML and Natural SQL DML provide clauses for specification of the multi-fetch-factor, the Natural program operates with one database row and from the program point of view only one row is received from or is send to the database.
This feature is only available with Natural SQL DML and has a lot of
impact on the program logic, as it allows the retrieval of multiple rows from
the database into the program storage by a single Natural SQL
SELECT statement into a set of arrays. Additionally it is possible
to insert multiple rows into the database from a set of arrays by the Natural
SQL INSERT statement.
Below is information on the following topics:
In standard mode, Natural does not read multiple records with a single database call; it always operates in a one-record-per-fetch mode. This kind of operation is solid and stable, but can take some time if a large number of database records are being processed.
To improve the performance of those programs, you can use the
Multi-Fetch Clause in the Natural DML FIND,
READ or
HISTOGRAM
statements. This allows you to specify the number of records read per database
access.
|
|
FIND
|
|
|
MULTI-FETCH
|
|
ON
|
|
|
READ
|
OFF
|
|||||||
HISTOGRAM
|
OF
multi-fetch-factor
|
Where the multi-fetch-factor is
either a constant or a variable with a format integer (I4).
To improve the performance of the Natural SQL SELECT
statements, you can use the WITH ROWSET POSITIONING FOR Clause to
specify a multi-fetch-factor.
|
|
WITH ROWSET
POSITIONING FOR
|
|
[:] row_hv |
|
ROWS
|
|
| integer |
At statement execution time, the runtime checks if a
multi-fetch-factor greater than 1 is
supplied for the database statement.
If the multi-fetch-factor
is
| less than or equal to 1 | the database call is continued in the usual one-record-per-access mode. |
| greater than 1 | the database call is prepared dynamically to read multiple
records (e.g. 10) with a single database access into an auxiliary buffer
(multi-fetch buffer). If successful, the first record is transferred into the
underlying data view. Upon the execution of the next loop, the data view is
filled directly from the multi-fetch buffer, without database access. After all
records are fetched from the multi-fetch buffer, the next loop results in the
next record set being read from the database. If the database loop is
terminated (either by end-of-records, ESCAPE,
STOP, etc.), the content
of the multi-fetch buffer is released.
|
The program does not receive "fresh" records from the database for every loop, but operates with images retrieved at the most recent multi-fetch access.
If a dynamic direction change (IN DYNAMIC...SEQUENCE) is
coded for a Natural DML READ or
HISTOGRAM statement,
the multi-fetch feature is not possible and leads to a corresponding syntax
error at compilation.
The size occupied by a database loop in the multi-fetch buffer is determined according to the rule:
| header + sqldaheader + columns*(sqlvar+lise) + mf*(udind + sum(collen) + sum(LF(columns) + sum(nullind)) |
| = |
| 32 + 16 + columns*(44+12) + mf*(1 + sum(collen) + sum(LF(column)) + sum(2)) |
where
header denotes the length of the header of a entry in the DB2 multifetch buffer, that is, 32
sqldaheader denotes the length of the header of a sqlda, that is, 16
columns denotes the number of receiving fields of a SQL request
sqlvar denotes the length of a sqlvar, that is, 44
lise denotes the length of a Natrual for DB2 specific sqlvar extension
mf denotes the multifetch factor, that is, the number of rows fetched by one database call
collen denotes the length of the receiving field
LF(column) denotes the size of the length field of the receiving field, that is, 0 for fixed length fields, 2 for variable length fields, and 4 for large object columns (LOBs)
nullind denotes the length of a null indicator, that is, 2
The multifetch buffer is released at terminal i/o in pseudo
conversional mode. Therefore there is no size limitation for the DB2 multifetch
buffer (DB2SIZE6). The buffer will be automatical enlarged if
necessary.
When multi-fetch is used, real database calls are only submitted to get a new set of records.
The TEST DBLOG Q facility is also called from the Natural
for DB2 multi fetch handler for every rowset fetch from DB2 and for every
record moved from the multi fetch buffer to the program storage. The events are
distinguished by the literal MULTI FETCH ... and <BUFF
FETCH ...
10:51:57 ***** NATURAL Test Utilities ***** 2006-01-27 User HGK - DBLOG Trace - Library NDB42 M No R SQL Statement (truncated) CU SN SREF M Typ SQLC/W Program Line LV _ 1 SELECT EMPNO,FIRSTNME,LASTNAM 01 01 0260 D DB2 MF000001 0260 01 _ 2 MULTI FETCH NEX 01 01 0260 D DB2 MF000001 0260 01 _ 3 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 4 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 5 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 6 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 7 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 8 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 9 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 10 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 11 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 12 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 13 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 14 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 15 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 16 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 _ 17 <BUFF FETCH NEX 00 00 0260 D DB2 MF000001 0260 01 Command ===> |
where column No represents the following:
| 1 | is a open cursor DB2 call. |
| 2 | is a "real" database call that reads a set of
records via multi-fetch (see MULTI FETCH NEX in column
SQL Statement).
|
| 3-17 |
are "no real" database calls, but only entries
that document that the program has received these records from the |
The feature allows programs to retrieve multiple rows from DB2 into arrays.
This feature is only available with the
SELECT
statement.
To use this feature
Set the compiler option
DB2ARRY=ON (by
using an OPTIONS
statement or the COMPOPT
command or the CMPO profile
parameter).
Specify a list of receiving arrays in the INTO clause
(see into-clause)
of the SELECT
statement.
Specify the number of rows to be retrieved from the database by a
single FETCH operation via the WITH ROWSET
POSITIONING Clause.
Specify a variable receiving the number of rows retrieved from the
database via the ROWS_RETURNED Clause.
DB2ARRY=ON is
necessary to allow the specification of arrays in the INTO clause
(see into-clause).
DB2ARRY=ON also prevents the usage of arrays as sending or
receiving fields for DB2 CHAR/VARCHAR
/GRAPHIC/VARGRAPHIC columns. Instead Natural scalar
fields with the appropriate length have to be used.
Each array specified in the INTO clause (see
into-clause)
has to be contiguous (one occurrence following immediately by another, this is
expected by DB2) and has to be one-dimensional. The arrays are filled from the
first occurrence (low) to last occurrence (high). The first array occurrences
compose the first row of the received rowset, the second array occurrences
compose the second row of the received rowset. The array occurrences of the nth
index compose the nth row returned from DB2. If an
LINDICATOR
Clause or
INDICATOR
Clause is used in the INTO clause for arrays,
the specified length indicators or null indicators have also to be arrays. The
number of occurrences of LINDICATOR and INDICATOR
arrays have to equal or greater than the number of occurrences of the master
array.
The WITH_ROWSET_POSITIONING Clause is used to specify the
number of rows to be retrieved from the database by one processing cycle. The
specified number has to be equal or smaller than the minimum of occurrences of
all specified arrays. If a variable, not a constant, is specified the actual
content of the variable will be used during each processing cycle. The
specified number has to be greater 0 and smaller than
32768.
The ROWS_RETURNED Clause is used to specify a variable,
which will contain the number of rows read from the database during the actual
fetch operation. The format of the variable has to be I4.
Natural Views: It is not possible to use Natural arrays of views in
the INTO clause (see
into-clause),
that is, the use of keyword VIEW is not possible.
The purpose of this feature is to reduce the number of database and
database interface calls for bulk batch processing. Therefore it is not
recommended to use this kind of programming in online CICS or IMS environments,
when terminal I/Os occur within open cursor loops; that is, the file server is
used. A fortiori it is not possible to perform a
Positioned
UPDATE or
Positioned
DELETE statement after terminal I/O.
Example:
DEFINE DATA LOCAL
01 NAME (A20/1:10)
01 ADDRESS (A100/1:10)
01 DATEOFBIRTH (A10/1:10)
01 SALARY (P4.2/1:10)
01 L$ADDRESS (I2/1:10)
01 ROWS (I4)
01 NUMBER (I4)
01 INDEX (I4)
END-DEFINE
OPTIONS DB2ARRY=ON
ASSIGN NUMBER := 10
SEL.
SELECT NAME, ADDRESS , DATEOFBIRTH, SALARY
INTO :NAME(*), /* <-- ARRAY
:ADDRESS(*) LINDICATOR :L$ADDRESS(*), /* <-- ARRAY
:DATEOFBIRTH(1:10), /* <-- ARRAY
:SALARY(01:10) /* <-- ARRAY
FROM NAT-DEMO
WHERE NAME > ' '
WITH ROWSET POSITIONING FOR :NUMBER ROWS /* <-- ROWS REQ
ROWS_RETURNED :ROWS /* <-- ROWS RET
IF ROWS > 0
FOR INDEX = 1 TO ROWS STEP 1
DISPLAY
INDEX (EM=99) *COUNTER (SEL.) (EM=99) ROWS (EM=99)
NAME(INDEX)
ADDRESS(INDEX) (AL=20)
DATEOFBIRTH(INDEX)
SALARY(INDEX)
END-FOR
END-IF
END-SELECT
END
The feature allows programs to insert multiple rows into a DB2 table from arrays.
This feature is only available with the Natural SQL
INSERT
statement.
To use this feature
Set the compiler option
DB2ARRY=ON (by
using an OPTIONS
statement or the COMPOPT
command or the CMPO profile
parameter).
Specify a list of sending arrays in the
VALUES
Clause of the Natural SQL
INSERT
statement.
Specify the number of rows to be inserted into the database by a
single Natural SQL INSERT statement via the
FOR
n ROWS Clause.
DB2ARRY=ON is
necessary to allow the specification of arrays in the
VALUES
Clause. DB2ARRY=ON also prevents the usage of
arrays as sending or receiving fields for DB2
CHAR/VARCHAR
/GRAPHIC/VARGRAPHIC columns. Instead Natural scalar
fields with the appropriate length have to be used.
Each array specified in the
VALUES
Clause has to be contiguous (one occurrence following
immediately by another, this is expected by DB2) and has to be one-dimensional.
The arrays are read from the first occurrence (low) to last occurrence (high).
The first array occurrences compose the first row inserted into the database,
the second array occurrences compose the second row inserted into the database.
The array occurrences of the nth index compose the nth row inserted into the
database. If an LINDICATOR
Clause or
INDICATOR
Clause is used in the VALUES Clause for
arrays, the specified length indicators or null indicators have also to be
arrays. The number of LINDICATOR and INDICATOR array
occurrences has to be equal or greater than the number of occurrences of the
master array.
The FOR
n ROWS Clause is used to
specify how many rows are to be inserted into the database table by one
INSERT statement.
The specified number has to be equal or smaller than the minimum of occurrences
of all specified arrays in the
VALUES
Clause. The specified number has to be greater than
0 and smaller than 32768.
It is not possible to use Natural arrays of views in the
VALUES
Clause, that is, the use of keyword
VIEW is not
possible.
Due to DB2 restrictions it is not possible to execute multiple row
inserts in static mode. Therefore, multiple row inserts are not generated
static and are always dynamically prepared and executed by Natural for DB2. The
Natural for DB2 static generation creates an assembler language SQL program,
which is precompiled by the DB2 precompiler, which in turn creates a DBRM
necessary for static execution. However, the DB2 assembler precompiler has no
support for host variable arrays. They can only be used when specified in a
SQLDA structure, which has to be build at execution time. But a static
INSERT with a multiple-row-insert VALUES clause does
not allow the specification of an SQLDA, but only host-variable arrays, which
are not supported by the DB2 assembler precompiler.
It is not possible to use Natural arrays of views in the
INTO clause (see
into-clause),
that is, the use of keyword
VIEW is not
possible.
Example:
DEFINE DATA LOCAL
01 NAME (A20/1:10) INIT <'ZILLER1','ZILLER2','ZILLER3','ZILLER4'
,'ZILLER5','ZILLER6','ZILLER7','ZILLER8'
,'ZILLER9','ZILLERA'>
01 ADDRESS (A100/1:10) INIT <'ANGEL STREET 1','ANGEL STREET 2'
,'ANGEL STREET 3','ANGEL STREET 4'
,'ANGEL STREET 5','ANGEL STREET 6'
,'ANGEL STREET 7','ANGEL STREET 8'
,'ANGEL STREET 9','ANGEL STREET 10'>
01 DATENATD (D/1:10) INIT <D'1954-03-27',D'1954-03-27',D'1954-03-27'
,D'1954-03-27',D'1954-03-27',D'1954-03-27'
,D'1954-03-27',D'1954-03-27',D'1954-03-27'
,D'1954-03-27'>
01 SALARY (P4.2/1:10) INIT <1000,2000,3000,4000,5000
,6000,7000,8000,9000,9999>
01 SALARY_N (N4.2/1:10) INIT <1000,2000,3000,4000,5000
,6000,7000,8000,9000,9999>
01 L§ADDRESS (I2/1:10) INIT <14,14,14,14,14,14,14,14,14,15>
01 N§ADDRESS (I2/1:10) INIT <00,00,00,00,00,00,00,00,00,00>
01 ROWS (I4)
01 INDEX (I4)
01 V1 VIEW OF NAT-DEMO_ID
02 NAME
02 ADDRESS (EM=X(20))
02 DATEOFBIRTH
02 SALARY
01 ROWCOUNT (I4)
END-DEFINE
OPTIONS DB2ARRY=ON /* <-- ENABLE DB2 ARRAY
ROWCOUNT := 10
INSERT INTO NAT-DEMO_ID
(NAME,ADDRESS,DATEOFBIRTH,SALARY)
VALUES
(:NAME(*), /* <-- ARRAY
:ADDRESS(*) /* <-- ARRAY
INDICATOR :N§ADDRESS(*) /* <-- ARRAY
LINDICATOR :L§ADDRESS(*), /* <-- ARRAY DB2 VCHAR
:DATENATD(1:10), /* <-- ARRAY NATURAL DATES
:SALARY_N(01:10) /* <-- ARRAY NATURAL NUMERIC
)
FOR :ROWCOUNT ROWS
SELECT * INTO VIEW V1 FROM NAT-DEMO_ID WHERE NAME > 'Z'
DISPLAY V1 /* <-- VERIFY INSERT
END-SELECT
BACKOUT
END
In contrast to the normal Natural error handling, where either an
ON ERROR statement is
used to intercept execution time errors or standard error message processing is
performed and program execution is terminated, the enhanced error handling of
Natural for DB2 provides an application controlled reaction to the encountered
SQL error.
Two Natural subprograms, NDBERR and
NDBNOERR, are
provided to disable the usual Natural error handling and to check the
encountered SQL error for the returned SQLCODE. This functionality replaces the
E function of the DB2SERV interface, which is still
provided but no longer documented.
For further information on Natural subprograms provided for DB2, see the section Interface Subprograms.
Example:
DEFINE DATA LOCAL
01 #SQLCODE (I4)
01 #SQLSTATE (A5)
01 #SQLCA (A136)
01 #DBMS (B1)
END-DEFINE
*
* Ignore error from next statement
*
CALLNAT 'NDBNOERR'
*
* This SQL statement produces an SQL error
*
INSERT INTO SYSIBH-SYSTABLES (CREATOR, NAME, COLCOUNT)
VALUES ('SAG', 'MYTABLE', '3')
*
* Investigate error
*
CALLNAT 'NDBERR' #SQLCODE #SQLSTATE #SQLCA #DBMS
*
IF #DBMS NE 2 /* not DB2
MOVE 3700 TO *ERROR-NR
END-IF
*
DECIDE ON FIRST VALUE OF #SQLCODE
VALUE 0, 100 /* successful execution
IGNORE
VALUE -803 /* duplicate row
/* UPDATE existing record
/*
IGNORE
NONE VALUE
MOVE 3700 TO *ERROR-NR
END-DECIDE
*
END