[jira] [Comment Edited] (CALCITE-704) FILTER clause for aggregate functions

["Julian Hyde (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14515988#comment-14515988 ] 

Julian Hyde edited comment on CALCITE-704 at 4/28/15 12:09 AM:
---------------------------------------------------------------

This and CALCITE-703 both require changes to AggregateCall constructor. To minimize the number of deprecated APIs we create, would be good to do them in the same minor release.


was (Author: julianhyde):
Both issues would require changes to AggregateCall constructor. To minimize the number of deprecated APIs we create, would be good to do them in the same minor release.

> FILTER clause for aggregate functions
> -------------------------------------
>
>                 Key: CALCITE-704
>                 URL: https://issues.apache.org/jira/browse/CALCITE-704
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Julian Hyde
>            Assignee: Julian Hyde
>
> The SQL standard provides a means to control which values are accumulated by an aggregate function.
> {code}aggregate function> ::=
>     COUNT <left paren> <asterisk> <right paren> [ <filter clause> ]
>   | <general set function> [ <filter clause> ]
>   | <binary set function> [ <filter clause> ]
>   | <ordered set function> [ <filter clause> ]
>   | <array aggregate function> [ <filter clause> ]
> <filter clause> ::=
>   FILTER <left paren> WHERE <search condition> <right paren>{code}
> For example, the following query sums the salary of all employees and female employees in a particular department:
> {code}SELECT deptno,
>   SUM(sal) AS all_sal,
>   SUM(sal) FILTER ( WHERE gender = 'F' ) AS female_sal
> FROM emp
> GROUP BY deptno{code}
> You could previously achieve this using {{SUM(CASE WHEN gender = 'F' THEN sal ELSE null END)}} but that trick only worked on certain aggregate functions.



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