November 2008
Intermediate to advanced
591 pages
17h 28m
English
Content preview from SQL in a Nutshell, 3rd Edition
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Name
SET CONSTRAINT Statement
The SET CONSTRAINT statement defines, for the current transaction, whether a deferrable constraint is checked after each DML statement or when the transaction is finally committed. If the session is not currently in an open transaction, thesetting applies to the next transaction.
Platform | Command |
MySQL | Not supported |
Oracle | Supported, with variations |
PostgreSQL | Supported, with variations |
SQL Server | Not supported |
SQL2003 Syntax
SET CONSTRAINT {constraint_name[, ...] | ALL} {DEFERRED | IMMEDIATE}Keywords
constraint_name[, . . . ] | ALLNames one or more deferrable constraints where the setting will apply. The keyword ALL sets the constraint mode for all deferrable constraints of the current transaction.
- DEFERRED
Checks the conditions specified by the deferrable constraint when the transaction is committed, rather than when the DML statements are issued.
- IMMEDIATE
Checks the conditions specified by the deferrable constraint immediately after each DML statement is issued, rather than when the transaction is committed.
Rules at a Glance
SET CONSTRAINT defines a value for the constraint mode of all deferrable constraints of the current transaction. If the session is not currently in a transaction, the SET CONSTRAINT statement applies to the next transaction issued during the session.
The following example sets all deferrable constraints to be checked immediately following the issuance of each DML statement:
SET CONSTRAINT ALL IMMEDIATE;
The next example sets two constraints to defer ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.