Implement FILTER-clause for aggregate functions [CORE5768]

[firebird-automations]

Submitted by: @mrotteveel

Implement FILTER-clause for aggregate functions (introduced in SQL:2003). This syntax allows for filtering before aggregation.

Basic example:

SUM(<expression>) FILTER(WHERE <condition>)

or with window functions:

SUM(<expression>) FILTER(WHERE <condition>) OVER (<window>)

Workarounds/alternative: use a CASE-expression within the aggregate function.

See also SQL:2016 10.9 <aggregate function> and https://modern-sql.com/feature/filter

Commits: 7206db3 e33ddf8

[firebird-automations]

Modified by: @asfernandes

assignee: Adriano dos Santos Fernandes [ asfernandes ]

[firebird-automations]

Modified by: @asfernandes

status: Open [ 1 ] => Resolved [ 5 ]

resolution: Fixed [ 1 ]

Fix Version: 4.0 Beta 1 [ 10750 ]

[firebird-automations]

Modified by: @pavel-zotov

status: Resolved [ 5 ] => Resolved [ 5 ]

QA Status: No test => Done successfully

[firebird-automations]

Modified by: @pavel-zotov

status: Resolved [ 5 ] => Closed [ 6 ]