This document covers the following topics:
For explanations of the symbols used in the syntax diagram, see Syntax Symbols.
Belongs to Function Group: Database Access and Update
The MERGE
statement updates a table using the specified
input data. Rows in the target table that match the input data are updated as
specified, and rows that do not exist in the target table are inserted.
The MERGE
statement belongs to the
SQL Extended Set.
This statement is available only with Natural for DB2.
Syntax Element | Description |
---|---|
MERGE
INTO |
MERGE INTO Clause:
|
table-name |
Table Name:
Identifies the target of the See table-name specification. |
[AS]
correlation-name
|
[AS] correlation-name
Clause:
Specifies an alternate name for the target table. The alternate name can be used as qualifier when referencing columns of the intermediate result table. |
include-columns |
Include Columns Clause:
Specifies a set of columns that are included, along with the
columns of the target table, in the result table of the For further details, see include-columns. |
USING
source-table |
USING source-table
Clause:
Specifies the values for the row data to merge into the target
table. See |
ON
search-condition |
ON search-condition
Clause:
Specifies join conditions between the
|
WHEN MATCHED THEN
update-operation |
WHEN MATCHED THEN
update-operation Clause:
Specifies the
|
WHEN NOT MATCHED THEN
insert-operation |
WHEN NOT MATCHED THEN
insert-operation Clause:
Specifies the
|
NOT
ATOMIC CONTINUE ON SQLEXCEPTION |
NOT ATOMIC CONTINUE ON SQLEXCEPTION
Clause:
Specifies whether merge processing continues in case an error occurred during processing one row of a set of source rows. |
QUERYNO
integer |
QUERYNO integer
Clause:
Specifies the number for this SQL statement that is used in
|
(VALUES |
) | |||
[AS ]
correlation-name (column-name,...)
|
Syntax Element | Description |
---|---|
VALUES |
VALUES introduces the specification
of values for the row data to merge into the target table.
|
values-single-row |
Specifies a single row of source data. See values-single-row. |
values-multiple-row |
Specifies multiple rows of source data. See values-multiple-row. |
[AS]
correlation-name |
Specifies a correlation name for the source table. |
column-name |
Specifies a column name to associate the input
data to the UPDATE SET
assignment-clause clause for an
UPDATE operation or the VALUES clause for an
INSERT
operation.
|
( | ,...) |
Syntax Element | Description |
---|---|
expression |
Scalar Expression:
Specifies a scalar expression as described in Scalar Expressions. |
NULL |
NULL Value:
Specifies the null value. |
FOR |
host-variable |
ROWS |
|||||||||||||||
( | ,...) |
Syntax Element | Description |
---|---|
expression |
Scalar Expression:
Specifies a scalar expression as described in Scalar Expressions. |
host-variable-array |
Host-Variable Array:
Specifies a host variable array or an index range of an array. If
|
NULL |
NULL Value:
Specifies the null value. |
FOR ...
ROWS |
Number of Rows to Merge:
This clause specifies the number of rows to merge.
|
UPDATE SET
assignment-clause |
Syntax Element | Description |
---|---|
UPDATE
SET |
Specifies the UPDATE operation to
be performed when the search-condition
evaluates to true.
See |
column-name = | expression | ,... | |||||
DEFAULT |
|||||||
NULL |
|||||||
(column-name,...) = ( | expression | ,...) | |||||
DEFAULT |
|||||||
NULL |
INSERT
[(column-name,...)]
VALUES (
|
,...) |
Update the inventory at a car dealership. Add new car model to the inventory or update information about existing car model that is already in the inventory.
DEFINE DATA LOCAL 01 #MODEL (A20) 01 #DELTA (I4) END-DEFINE * Setup input host variables ASSIGN #MODEL = ‘Grand Turbo’ ASSIGN #DELTA := 5 * Insert/Update into INVENTORY table MERGE INTO CDS-INVENTORY T USING (VALUES (:#MODEL, :#DELTA)) AS S(MODEL, DELTA) ON T.MODEL = S.MODEL WHEN MATCHED THEN UPDATE SET T.QUANTITY = T.QUANTITY + S.DELTA WHEN NOT MATCHED THEN INSERT VALUES (S.MODEL, S.DELTA) END TRANSACTION END
Update the inventory at a car dealership. Add new car models to the inventory and update information about car models that are already in the inventory. Input comes from Natural arrays. Array specific code is shown in bold face type.
OPTIONS DB2ARRY ON DEFINE DATA LOCAL 01 #MODEL_ARR (A20/1:20) 01 #DELTA_ARR (I4/1:20)) 01 #ROW-COUNT (I4) 01 #NUM-ERRORS (I4) 01 #SQLCODE (I4) 01 #SQLSTATE (A5) 01 #ROW-NUM (I4) END-DEFINE * Setup input host variables ASSIGN #MODEL_ARR(1) = ‘Grand Turbo’ ASSIGN #DELTA_ARR(1) := 5 ASSIGN #MODEL_ARR(2) = ‘Blue Car’ ASSIGN #DELTA_ARR(2) := 3 . . . * Insert/Update into INVENTORY table CALLNAT 'NDBNOERR' MERGE INTO CDS-INVENTORY T USING (VALUES (:#MODEL_ARR(*), :#DELTA_ARR(*)) FOR 20 ROWS) AS S(MODEL, DELTA) ON T.MODEL = S.MODEL WHEN MATCHED THEN UPDATE SET T.QUANTITY = T.QUANTITY + S.DELTA WHEN NOT MATCHED THEN INSERT VALUES (S.MODEL, S.DELTA) NOT ATOMIC CONTINUE ON SQLEXCEPTION * Check outcome of MERGE PROCESS SQL SYSIBM-SYSDUMMY1 <<GET DIAGNOSTICS :#ROW-COUNT = ROW_COUNT ,:#NUM-ERRORS = NUMBER>> WRITE 'Number of rows merged :' #ROW-COUNT / 'NUMBER OF ERRORS :' #NUM-ERRORS IF #NUM-ERRORS > 0 FOR #I = 1 TO #NUM-ERRORS PROCESS SQL SYSIBM-SYSDUMMY1 <<GET DIAGNOSTICS CONDITION :#I :#SQLCODE = DB2_RETURNED_SQLCODE, :#SQLSTATE = RETURNED_SQLSTATE, :#ROW_NUM = DB2_ROW_NUMBER>> PRINT 'DB2_RETURNED_SQLCODE:' #SQLCODE 'RETURNED_SQLSTATE:' #SQLSTATE 'DB2_ROW_NUMBER:' #ROW_NUM (EM=99Z) END-FOR END-IF END TRANSACTION END