Support percentile_cont, other ordered-set aggregate

[Former user]

Oracle has a very wierd syntax for a function called percentile_cont. I can use text to perform it, but it would be nice to have an easy way to use the function from sqlalchemy, as this function needs to recieve a column (or expression) in the "order by" part...

Function Description

[Former user]

submitted by [e-mail]

[Mike Bayer]

it would live in the oracle package and would need a full functional spec for review.

[Mike Bayer]

this is SQL standard:

Postgresql: http://www.postgresql.org/docs/current/static/functions-aggregate.html SQL Server: https://msdn.microsoft.com/en-us/library/Hh231473.aspx Oracle: http://docs.oracle.com/cd/B19306_01/server.102/b14200/functions110.htm

easy win see if we can throw this in

[Mike Bayer]

lets do evertyhing else under ordered-set aggregate functions and Hypothetical-Set Aggregate Functions at http://www.postgresql.org/docs/current/static/functions-aggregate.html:

dense_rank rank cume_dist percent_rank mode percentile_cont percentile_disc

[Mike Bayer]

dense_rank - Integer

rank - Integer

cume_dist - Numeric

percent_rank - Numeric

mode - same as sort expression

percentile_cont -same as sort expression

percentile_disc - same as sort expression

percentile_cont, given Array - Array of sort expression - see #3516

percentile_disc, given Array - Array of sort expression - see #3516

[Mike Bayer]

• Added support for "set-aggregate" functions of the form <function> WITHIN GROUP (ORDER BY <criteria>), using the method :class:.FunctionElement.within_group. A series of common set-aggregate functions with return types derived from the set have been added. This includes functions like :class:.percentile_cont, :class:.dense_rank and others. fixes #1370
• make sure we use func.name for all _literal_as_binds in functions.py so we get consistent naming behavior for parameters.

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