[jira] [Commented] (DERBY-6659) The Reference Guide should state how long a SET CONSTRAINTS command is good for

["Rick Hillegas (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-6659?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14059284#comment-14059284 ] 

Rick Hillegas commented on DERBY-6659:
--------------------------------------

Thanks, Kim. Looks good. +1

> The Reference Guide should state how long a SET CONSTRAINTS command is good for
> -------------------------------------------------------------------------------
>
>                 Key: DERBY-6659
>                 URL: https://issues.apache.org/jira/browse/DERBY-6659
>             Project: Derby
>          Issue Type: Improvement
>          Components: Documentation
>    Affects Versions: 10.11.0.0
>            Reporter: Rick Hillegas
>            Assignee: Kim Haase
>         Attachments: DERBY-6659.diff, rrefsqljsetconstr.html
>
>
> A SET CONSTRAINTS command changes the state of a constraint only until the transaction ends (or another, overriding SET CONSTRAINTS command is issued). Once the transaction ends, the constraint reverts to the default behavior declared for it at CREATE/ALTER TABLE time. However, this behavior is not clear from the reference material on SET CONSTRAINTS: https://builds.apache.org/job/Derby-docs/lastSuccessfulBuild/artifact/trunk/out/ref/rrefsqljsetconstr.html
> The following script shows this behavior:
> {noformat}
> connect 'jdbc:derby:memory:db;create=true' as conn1;
> autocommit off;
> create table tprim
> (
>     keyCol  int primary key
> );
> create table tref
> (
>     refCol  int,
>     constraint refcon foreign key( refCol ) references tprim( keyCol ) deferrable
> );
> insert into tprim( keyCol ) values ( 1 ), ( 2 ), ( 3 );
> commit;
> set constraints refcon deferred;
> -- succeeds because we switched to deferred mode for this transaction
> insert into tref( refCol ) values ( 4 );
> rollback;
> -- but fails the second time because the end of the previous transaction
> -- reverted the refcon constraint to its default (immediate) mode
> insert into tref( refCol ) values ( 4 );
> {noformat}



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