[jira] [Commented] (DERBY-3155) Support for SQL:2003 MERGE statement

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    [ https://issues.apache.org/jira/browse/DERBY-3155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13892406#comment-13892406 ] 

ASF subversion and git services commented on DERBY-3155:
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Commit 1564874 from [~rhillegas] in branch 'code/trunk'
[ https://svn.apache.org/r1564874 ]

DERBY-3155: Revamp how columns referenced by WHEN [ NOT ] MATCHED clauses are linked to the columns coming back from the driving left join of a MERGE statement; commit derby-3155-20-aa-reworkColumnMatching.diff.

> 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, derby-3155-12-aa-canOmitInsertColumnList.diff, derby-3155-13-aa-allowSystemAndTempTables.diff, derby-3155-14-aa-replaceCorrelationNamesOnLeftSideOfSETclauses.diff, derby-3155-15-aa-replumbMergeResultSetCleanup.diff, derby-3155-16-aa-treatCurrentRowLocationNodeLikeBaseColumnNode.diff, derby-3155-17-aa-serializingRowLocations.diff, derby-3155-18-aa-basicView.diff, derby-3155-19-aa-forbidSubqueriesInMatchedClauses.diff, derby-3155-20-aa-reworkColumnMatching.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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