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https://issues.apache.org/jira/browse/DERBY-3155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13870676#comment-13870676
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Knut Anders Hatlen commented on DERBY-3155:
-------------------------------------------
Here's another NPE:
{noformat}
ij> create table t1(x int);
0 rows inserted/updated/deleted
ij> create table t2(x int);
0 rows inserted/updated/deleted
ij> merge into t1 using t2 on t1.x=t2.x when matched then update set x =
(select count(*) from t2);
ERROR XJ001: Java exception: ': java.lang.NullPointerException'. (errorCode = 0)
java.lang.NullPointerException
at
org.apache.derby.impl.sql.compile.SelectNode.getFinalCostEstimate(SelectNode.java:2224)
at
org.apache.derby.impl.sql.compile.SubqueryNode.generateExpression(SubqueryNode.java:1936)
at
org.apache.derby.impl.sql.compile.ResultColumn.generateExpression(ResultColumn.java:1056)
at
org.apache.derby.impl.sql.compile.ResultColumnList.generateEvaluatedRow(ResultColumnList.java:1452)
at
org.apache.derby.impl.sql.compile.MatchingClauseNode.generateInsertUpdateRow(MatchingClauseNode.java:1255)
at
org.apache.derby.impl.sql.compile.MatchingClauseNode.generate(MatchingClauseNode.java:1146)
at
org.apache.derby.impl.sql.compile.MergeNode.generate(MergeNode.java:770)
at
org.apache.derby.impl.sql.compile.StatementNode.generate(StatementNode.java:317)
at
org.apache.derby.impl.sql.GenericStatement.prepMinion(GenericStatement.java:547)
at
org.apache.derby.impl.sql.GenericStatement.prepare(GenericStatement.java:99)
at
org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.prepareInternalStatement(GenericLanguageConnectionContext.java:1116)
at
org.apache.derby.impl.jdbc.EmbedStatement.execute(EmbedStatement.java:682)
at
org.apache.derby.impl.jdbc.EmbedStatement.execute(EmbedStatement.java:631)
at org.apache.derby.impl.tools.ij.ij.executeImmediate(ij.java:367)
at org.apache.derby.impl.tools.ij.utilMain.doCatch(utilMain.java:527)
at
org.apache.derby.impl.tools.ij.utilMain.runScriptGuts(utilMain.java:369)
at org.apache.derby.impl.tools.ij.utilMain.go(utilMain.java:245)
at org.apache.derby.impl.tools.ij.Main.go(Main.java:229)
at org.apache.derby.impl.tools.ij.Main.mainCore(Main.java:184)
at org.apache.derby.impl.tools.ij.Main.main(Main.java:75)
at org.apache.derby.tools.ij.main(ij.java:59)
{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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