mirror of
https://github.com/FirebirdSQL/firebird.git
synced 2025-01-23 00:03:02 +01:00
56 lines
1.4 KiB
Plaintext
56 lines
1.4 KiB
Plaintext
-----------------
|
|
MERGE statement
|
|
-----------------
|
|
|
|
Function:
|
|
Read data from the source and INSERT or UPDATE in the target table depending on a
|
|
condition.
|
|
|
|
Author:
|
|
Adriano dos Santos Fernandes <adrianosf@uol.com.br>
|
|
|
|
Format:
|
|
<merge statement> ::=
|
|
MERGE
|
|
INTO <table or view> [ [AS] <correlation name> ]
|
|
USING <table or view or derived table> [ [AS] <correlation name> ]
|
|
ON <condition>
|
|
[ <merge when matched> ]
|
|
[ <merge when not matched> ]
|
|
|
|
<merge when matched> ::=
|
|
WHEN MATCHED THEN
|
|
UPDATE SET <assignment list>
|
|
|
|
<merge when not matched> ::=
|
|
WHEN NOT MATCHED THEN
|
|
INSERT [ <left paren> <column list> <right paren> ]
|
|
VALUES <left paren> <value list> <right paren>
|
|
|
|
Syntax rules:
|
|
1. At least one of <merge when matched> and <merge when not matched> should be specified
|
|
and each one should not be specified more than one time.
|
|
|
|
Scope:
|
|
DSQL, PSQL
|
|
|
|
Examples:
|
|
1.
|
|
MERGE
|
|
INTO customers c
|
|
USING (SELECT * FROM customers_delta WHERE id > 10) cd
|
|
ON (c.id = cd.id)
|
|
WHEN MATCHED THEN
|
|
UPDATE SET
|
|
name = cd.name
|
|
WHEN NOT MATCHED THEN
|
|
INSERT (id, name)
|
|
VALUES (cd.id, cd.name)
|
|
|
|
Notes:
|
|
A right join is made between INTO and USING tables using the condition.
|
|
UPDATE is called when a record exist in the left table (INTO), otherwise
|
|
INSERT is called.
|
|
|
|
If no record is returned in the join, INSERT is not called.
|