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https://issues.apache.org/jira/browse/HIVE-9008?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14231923#comment-14231923
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Xuefu Zhang commented on HIVE-9008:
-----------------------------------
This JIRA also needs a better title. The problem described here seems similar
to that in HIVE-8009.
> primary table in union
> ----------------------
>
> Key: HIVE-9008
> URL: https://issues.apache.org/jira/browse/HIVE-9008
> Project: Hive
> Issue Type: Sub-task
> Reporter: Pengcheng Xiong
>
> Following http://dev.mysql.com/doc/refman/5.0/en/union.html
> The column names from the first SELECT statement are used as the column names
> for the results returned. Selected columns listed in corresponding positions
> of each SELECT statement should have the same data type. (For example, the
> first column selected by the first statement should have the same type as the
> first column selected by the other statements.)
> If the data types of corresponding SELECT columns do not match, the types and
> lengths of the columns in the UNION result take into account the values
> retrieved by all of the SELECT statements.
> We can say
> select A.id from A
> union
> select B.id from B
> order by id
> We can say
> select A.id as a from A
> union
> select B.id from B
> order by a
> We can NOT say
> select A.id as a from A
> union
> select B.id from B
> order by A.id
> ERROR 1054 (42S22): Unknown column 'A.id' in 'order clause'
> We can NOT say
> select A.id as a from A
> union
> select B.id from B
> order by B.id
> ERROR 1054 (42S22): Unknown column 'B.id' in 'order clause'
> We can say
> select A.id as a from A
> union
> (select B.id from B
> order by B.id)
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