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https://issues.apache.org/jira/browse/DERBY-3155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13894574#comment-13894574
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Knut Anders Hatlen commented on DERBY-3155:
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The syntax description in the functional specification says that the source
table and the target table can have a correlation name. It doesn't seem to
allow column lists to go with the correlation names (since it says
correlationName, not correlationClause). The actually implemented syntax seems
to accept column lists, though, and the column names can be used in the ON
clause:
{noformat}
ij> create table t(x int);
0 rows inserted/updated/deleted
ij> merge into t t1(a) using t t2(b) on a=b when not matched then insert values
(1);
0 rows inserted/updated/deleted
WARNING 02000: No row was found for FETCH, UPDATE or DELETE; or the result of a
query is an empty table.
{noformat}
However, the specified column name cannot be used in the mergeInsert clause:
{noformat}
ij> merge into t t1(a) using t t2(b) on a=b when not matched then insert values
(b);
ERROR 42X04: Column 'B' is either not in any table in the FROM list or appears
within a join specification and is outside the scope of the join specification
or appears in a HAVING clause and is not in the GROUP BY list. If this is a
CREATE or ALTER TABLE statement then 'B' is not a column in the target table.
{noformat}
If I read the SQL standard correctly, it doesn't allow a column list for the
target table. It does seem to allow a column list for the source table, though.
> 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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