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https://issues.apache.org/jira/browse/CALCITE-5583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17969524#comment-17969524
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Mihai Budiu commented on CALCITE-5583:
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I actually don't understand exactly what the problem is that is being solved.
As stated in the JIRA, some Calcite IR programs will generate SQL that cannot
be executed on some databases. That is not a problem in itself, since you can
create Calcite programs that are invalid in some dialects.
> JDBC adapter generates 'SELECT *', which is invalid SQL if there are
> duplicate column names
> -------------------------------------------------------------------------------------------
>
> Key: CALCITE-5583
> URL: https://issues.apache.org/jira/browse/CALCITE-5583
> Project: Calcite
> Issue Type: Bug
> Reporter: libopeng
> Assignee: libopeng
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> JDBC adapter generates 'SELECT *', which is invalid SQL if there are
> duplicate column names
> {code:java}
> LogicalProject(c0=[$0], c00=[$1])
> LogicalJoin(condition=[=($0, $1)], joinType=[inner])
> LogicalProject(c0=[$0])
> LogicalTableScan(table=[[scott, EMP]])
> LogicalProject(c0=[$0])
> LogicalTableScan(table=[[scott, EMP]]){code}
> to sql
> {code:java}
> SELECT *
> FROM (SELECT "EMPNO" AS "c0"
> FROM "scott"."EMP") AS "t"
> INNER JOIN (SELECT "EMPNO" AS "c0"
> FROM "scott"."EMP") AS "t0" ON "t"."c0" = "t0"."c0" {code}
> When this sql is a subquery, it can be wrong
> {code:java}
> select *
> from "EMPNO" t1
> left join (
> SELECT * FROM (SELECT "EMPNO" AS "c0" FROM "scott"."EMP") AS "t" INNER JOIN
> (SELECT "EMPNO" AS "c0" FROM "scott"."EMP") AS "t0" ON "t"."c0" = "t0"."c0"
> ) t2
> on t1.EMPNO=t2."c0"{code}
> {color:#ff0000}fault: 'column reference "c0" is ambiguous' error when
> executing in postgresql{color}
>
>
>
>
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