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https://issues.apache.org/jira/browse/DERBY-1773?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12835175#action_12835175
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Knut Anders Hatlen commented on DERBY-1773:
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My understanding is that "FOR UPDATE OF C1,C2" means that the cursor should be
updatable, but you can only update the columns C1 and C2 using that cursor. If
there's an alias on C1 or C2, the statement should fail. Aliases on other
columns than C1 and C2 should be allowed, and the cursor should still be
updatable if they are aliased. If I read the patch correctly, it will make the
cursor read only as long as there is at least one column that's aliased. I
don't think it's a big usability issue if we choose to disallow aliases
altogether on updatable cursors, but that would require changes to the
reference manual [1] and probably also warrant a release note, so I'd prefer
not to impose that restriction.
I agree that the two different ways of aliasing (C2 AS A2 vs T1 AS A(A1,A2))
are equivalent with regard to this issue and should be handled the same way.
I also agree that FOR UPDATE with no column list, or an implicit FOR UPDATE
clause (DERBY-231), means that all columns are updatable. Perhaps the
alternative, more dynamic semantics are more convenient in some cases, but we
already have syntax for making just a subset of the columns updatable, so I
don't think it adds much value.
[1]
http://db.apache.org/derby/docs/dev/ref/rrefsqlj41360.html#rrefsqlj41360__sqlj15384
> insertRow() and updateRow() fail with syntax error when column has an alias
> ---------------------------------------------------------------------------
>
> Key: DERBY-1773
> URL: https://issues.apache.org/jira/browse/DERBY-1773
> Project: Derby
> Issue Type: Bug
> Components: JDBC
> Affects Versions: 10.2.1.6
> Reporter: Knut Anders Hatlen
> Assignee: Bryan Pendleton
> Priority: Minor
> Attachments: Alias.java, NoUpdatesToAliasedColumnsWithTest.diff
>
>
> When the select query used in an updatable result set has column aliases, a
> syntax error is thrown when executing ResultSet.insertRow() and
> ResultSet.updateRow(). The problem is seen on embedded and client. Repro is
> attached.
> Exception in thread "main" ERROR 42X14: 'A1' is not a column in table or VTI
> 'APP.T'.
> at
> org.apache.derby.iapi.error.StandardException.newException(StandardException.java:316)
> at
> org.apache.derby.impl.sql.compile.ResultColumn.bindResultColumnByName(ResultColumn.java:677)
> at
> org.apache.derby.impl.sql.compile.ResultColumnList.bindResultColumnsByName(ResultColumnList.java:682)
> at
> org.apache.derby.impl.sql.compile.ResultSetNode.bindResultColumns(ResultSetNode.java:683)
> at
> org.apache.derby.impl.sql.compile.SelectNode.bindResultColumns(SelectNode.java:742)
> at
> org.apache.derby.impl.sql.compile.UpdateNode.bind(UpdateNode.java:349)
> at
> org.apache.derby.impl.sql.GenericStatement.prepMinion(GenericStatement.java:345)
> at
> org.apache.derby.impl.sql.GenericStatement.prepare(GenericStatement.java:111)
> at
> org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.prepareInternalStatement(GenericLanguageConnectionContext.java:723)
> at
> org.apache.derby.impl.jdbc.EmbedResultSet.updateRow(EmbedResultSet.java:3734)
> at Alias.main(Alias.java:15)
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