UPDATELOB [OF ]
[RECORD ]
[(r)] [IN ]
[FILE ] view-name |
|||||
[PASSWORD =operand1]
|
|||||
[CIPHER =operand2]
|
|||||
[[STARTING ]
[AT ] OFFSET
[=] operand3]
|
|||||
TRUNCATE |
This document covers the following topics:
For an explanation of the symbols used in the syntax diagram, see Syntax Symbols.
Related Statements: READ
| FIND
| GET
| READLOB
|
UPDATE
Belongs to Function Group: Database Access and Update
The UPDATELOB
statement is used to update a data segment of
a LOB field (Large OBject field) in a database record. The position of the
value modification is freely selectable. The record to be updated must have
been previously selected with a FIND
, READ
, GET
statement or created with a
STORE
statement
The use of the UPDATELOB
statement causes each record read
for processing in the corresponding FIND
, READ
or
GET
statement to be placed in exclusive hold.
For further information, see Record Hold Logic in the Programming Guide.
The UPDATELOB
statement
can only be used for access to Adabas databases;
must not be entered on the same line as the statement used to select the record to be updated;
is only applicable to update a single LOB field.
Operand Definition Table:
Operand | Possible Structure | Possible Formats | Referencing Permitted | Dynamic Definition | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
operand1
|
C | S | A | yes | no | |||||||||||||||
operand2
|
C | S | N | yes | no | |||||||||||||||
operand3
|
C | S | N | P | I | B * | yes | no |
* Format B of operand3
may be
used with a length of less than or equal to 4.
Syntax Element Description:
Syntax Element | Description |
---|---|
(r) |
Statement Reference:
The notation If no reference is specified, the Note: |
view-name |
View Name:
As
|
PASSWORD and CIPHER Clauses:
The The |
|
STARTING AT
OFFSET=operand3 |
STARTING AT OFFSET Clause:
Provides the start offset within the LOB field, where the operation
is executed. The leftmost byte of the LOB field is offset zero
(
If this clause is omitted, start offset ( |
TRUNCATE Clause:
If If If this clause is omitted, the data behind the inserted segment is preserved. |
The Natural system variable *NUMBER
is provided with the UPDATELOB
statement.
The format/length of this system variable is P10. This format/length cannot be changed.
System Variable | Explanation |
---|---|
*NUMBER |
The system variable
*NUMBER returns the sum of the start offset and
the number of characters inserted. This value represents the starting offset
for the next UPDATELOB , if a consecutive area of the LOB field is
replaced with multiple calls.
The number of inserted characters is either the byte length of the
LOB segment defined in the view or zero ( The |
An UPDATELOB
operates a record which was set into hold by
an associated FIND
,
READ
,
GET
or
STORE
statement. The link is
either implicit via the current active reference or explicit with
(r)
notation.
The view used by the associated statement and the view used by the
UPDATELOB
have to access the same database and file number. This
is automatically assured if the views are derived from the same data definition
module (DDM).
If the insert position
operand3
is greater than the LOB
length, the gap is filled with blanks. This means you may update a LOB field at
a position which is beyond its length.
You cannot replace m bytes with n bytes - or in other words, it is not admissible to substitute a LOB part with a data segment of different length.
The value returned with *NUMBER
is the
high-water mark indicating the position inside the LOB where the last insert
has ended. If a number of consecutive update operations is demanded, this value
should always be retained as STARTING AT
value for the next
UPDATELOB
execution.
DEFINE DATA LOCAL 1 V1 VIEW OF .. 2 PERSONNEL-ID 2 NAME 1 V2 VIEW OF .. 2 LOBFIELD_SEGMENT /* LOB field defined in DDM with (A1024). END-DEFINE * **=================================================== ** Store new record **=================================================== V1.PERSONNEL-ID := '12345678' V1.NAME := 'Smith' LAB1. STORE V1 /* Store new record with 2 fixed length fields. * MOVE ALL 'X' TO LOBFIELD_SEGMENT **=================================================== ** Update LOB field **=================================================== UPDATELOB (LAB1.) IN FILE V2 /* INSERT 1 KB SEGMENT (LOBFIELD_SEGMENT) /* IN LOB. STARTING AT OFFSET = 2048 /* STORE DATA IN LOB RANGE 2049-3072. /* FIRST 2 KBS ARE AUTO-FILLED WITH BLANKS BY THE DB. END TRANSACTION END
DEFINE DATA LOCAL 1 V1 VIEW OF EMPLOYEES-V2009 2 PERSONNEL-ID 2 NAME 2 L@PICTURE 1 V2 VIEW OF EMPLOYEES-V2009 2 PICTURE_SEGMENT /* LOB field defined in DDM with (A1024). 2 REDEFINE PICTURE 3 PICTURE_B (B1024) 1 #OFF (I4) END-DEFINE * **=================================================== ** Read record to be updated **=================================================== LAB1. READ (1) V1 BY PERSONNEL-ID = '60008339' /* Read record and set into exclusive hold. RESET #OFF /* Start to overwrite LOB field from the beginning. /*=================================================== /* Read data from work file and put into LOB field /*=================================================== READ WORK FILE 7 PICTURE_B /* Start to read picture data (.jpg) from work file. LAB2. UPDATELOB (LAB1.) IN FILE V2 STARTING AT OFFSET #OFF #OFF := *NUMBER(LAB2.) /* Keep next position to append. END-WORK END-READ **=================================================== END TRANSACTION END
DEFINE DATA LOCAL 1 V1 VIEW OF EMPLOYEES-V2009 2 PERSONNEL-ID 2 NAME 2 L@PICTURE 1 V2 VIEW OF EMPLOYEES-V2009 1 V3 VIEW OF EMPLOYEES-V2009 2 PICTURE_SEGMENT /* LOB field defined in DDM with (A1024). END-DEFINE * **=================================================== ** Read record to be updated **=================================================== LAB1. READ V1 BY PERSONNEL-ID /* Read records. IF L@PICTURE > 10240 THEN /* Check if LOB length is too high. LAB2. GET V2 RECORD *ISN(LAB1.) /* Set record to be updated into exclusive hold. UPDATELOB (LAB2.) IN FILE V3 STARTING AT OFFSET 10240 TRUNCATE AT OFFSET /* Truncate LOB data beyond 10KB. END TRANSACTION END-IF END-READ END
DEFINE DATA LOCAL 1 V1 VIEW OF .. 2 NAME 1 V2 VIEW OF .. 2 DOCUMENT_SEGMENT /* LOB field defined in DDM with (A100). 1 #ISN (I4) 1 #POS (I4) 1 #LENGTH (I4) INIT <100> END-DEFINE * **=================================================== ** Read record to be updated **=================================================== INPUT (AD=T) / ' Read record (ISN):' #ISN * G1. GET V1 RECORD #ISN /* Get record with ISN and set into exclusive hold. * **=================================================== ** Read LOB data and update segment of LOB field **=================================================== R1. READLOB V2 WITH ISN = #ISN STARTING AT OFFSET = 3000 .. #POS := *NUMBER(R1.) - #LENGTH .. IF .. DOCUMENT_SEGMENT := .. UPDATELOB (G1.) IN FILE V2 /* Update current segment in LOB field. STARTING AT OFFSET #POS END-IF .. END-READLOB * END TRANSACTION END