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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-3155) Support for SQL:2003 MERGE statement
Date Tue, 11 Feb 2014 12:48:21 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13897816#comment-13897816
] 

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

Thanks for adding support for ? parameters, Rick. It doesn't look like the parameter values
are always seen by the MERGE statement, though:

{noformat}
ij> create table t1(x int);
0 rows inserted/updated/deleted
ij> create table t2(x int);
0 rows inserted/updated/deleted
ij> insert into t2 values 1;
1 row inserted/updated/deleted
ij> execute 'merge into t1 using t2 on t1.x=t2.x when not matched then insert values (?)'
using 'values 1';
IJ WARNING: Autocommit may close using result set
1 row inserted/updated/deleted
ij> select * from t1;
X          
-----------
NULL       

1 row selected
{noformat}

I had expected the value 1 rather than NULL to be inserted into T1 here.

> 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, derby-3155-21-ac-cleanupAndForbidSynonyms.diff,
derby-3155-22-ad-testIdentifiersOnLeftSideOfSetClauses.diff, derby-3155-23-aa-forbidDerivedColumnLists.diff,
derby-3155-24-aa-supportParameters.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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