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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-3155) Support for SQL:2003 MERGE statement
Date Mon, 13 Jan 2014 15:15:03 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13869605#comment-13869605
] 

Knut Anders Hatlen commented on DERBY-3155:
-------------------------------------------

I've discovered one more problem:

{noformat}
ij> create view singlerow(x) as values 1;
0 rows inserted/updated/deleted
ij> create table t1(x int);
0 rows inserted/updated/deleted
ij> create table t2(y int);
0 rows inserted/updated/deleted
ij> create trigger tr after insert on t1 referencing new as new for each row merge into
t2 using singlerow on t2.y = new.x when not matched then insert (y) values (new.x);
0 rows inserted/updated/deleted
ij> insert into t1 values 1,2,3,4,5,4,3,2,1,1,1,2,3,100;
ERROR XJ001: Java exception: 'ASSERT FAILED ProjectRestrictResultSet already open: org.apache.derby.shared.common.sanity.AssertFailure'.
(errorCode = 0)
{noformat}

> Support for SQL:2003 MERGE statement
> ------------------------------------
>
>                 Key: DERBY-3155
>                 URL: https://issues.apache.org/jira/browse/DERBY-3155
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Trejkaz
>            Assignee: Rick Hillegas
>              Labels: derby_triage10_10
>         Attachments: MergeStatement.html, MergeStatement.html, MergeStatement.html, derby-3155-01-ac-grammar.diff,
derby-3155-02-ag-fixParserWarning.diff, derby-3155-03-ae-backingStoreHashtableWithRowLocation.diff,
derby-3155-03-af-backingStoreHashtableWithRowLocation.diff, derby-3155-03-ag-backingStoreHashtableWithRowLocation.diff,
derby-3155-03-ah-backingStoreHashtableWithRowLocation.diff, derby-3155-04-ae-deleteAction.diff,
derby-3155-04-af-deleteAction.diff, derby-3155-05-aa-triggerTransitionTableAsTarget.diff,
derby-3155-06-aa-triggerTransitionTableAsSource.diff, derby-3155-07-ad-insertAction.diff,
derby-3155-08-ah-updateAction.diff, derby-3155-09-aa-correlationNames.diff, derby-3155-10-aa-correlationNames.diff,
derby-3155-11-ab-beforeTriggersCantFireMerge.diff
>
>
> A relatively common piece of logic in a database application is to check for a row's
existence and then either update or insert depending on its existence.
> SQL:2003 added a MERGE statement to perform this operation.  It looks like this:
>     MERGE INTO table_name USING table_name ON (condition)
>     WHEN MATCHED THEN UPDATE SET column1 = value1 [, column2 = value2 ...]
>     WHEN NOT MATCHED THEN INSERT column1 [, column2 ...] VALUES (value1 [, value2 ...])

> At the moment, the only workaround for this would be to write a stored procedure to do
the same operation, or to implement the logic client-side.



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