[jira] [Commented] (DRILL-2239) Confusing error message "Column 't1' is ambiguous" for _table_ name t1

["Jinfeng Ni (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DRILL-2239?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14319334#comment-14319334 ] 

Jinfeng Ni commented on DRILL-2239:
-----------------------------------

The error message seems to be fine.

In ON clause, expression "( t1 IS NULL AND t2 IS NULL)" , "t1" is interpreted as a column name.  Unqualified identifier in the expression is interpreted as a column name. Qualified identifier like "t1.key",  the qualifier is interpreted as table name or alias, and the second part is interpreted as column name.




> Confusing error message "Column 't1' is ambiguous" for _table_ name t1
> ----------------------------------------------------------------------
>
>                 Key: DRILL-2239
>                 URL: https://issues.apache.org/jira/browse/DRILL-2239
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: SQL Parser
>            Reporter: Daniel Barclay (Drill/MapR)
>            Assignee: Aman Sinha
>            Priority: Minor
>
> The error message about the erroneous use of "t1" in "t1 IS NULL" in this query:
>  select * 
>             from               dfs_test.`xxx/jsoninput/nullable1U.json` t1
>                left outer join dfs_test.`xxx/jsoninput/nullable2U.json` t2
>                   on ( t1.key = t2.key OR ( t1 IS NULL AND t2 IS NULL) )
> says "Column 't1' is ambiguous" even though t1 is not a column name and isn't ambiguous.



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