MySQL and window functions

MySQLwindow functions

It seems that MySQL does not support window functions.
E.g. the simple: COUNT(*) OVER() AS cnt does not work.
What I am not sure is if this applies to commercial version as well (I assume the community version is limited subset).
If not, how does one work around this missing feature?

Best Answer

MySQL does not support Window Functions(*). There is what we call "a poor man's window function" in the form of GROUP_CONCAT().

There are plenty of tricks using GROUP_CONCAT to emulate window functions. They are not as pretty (syntactically) and are sometimes too limited. I've written a few. See my blog post complaining about the missing window functions, and linking to various solutions based on GROUP_CONCAT.

In particular, Selecting a specific non aggregated column data in GROUP BY and SQL: selecting top N records per group, another solution might be of interest to you and could give you a kick start.

Things you should note about GROUP_CONCAT():

  • Can use DISTINCT
  • Can use ORDER BY ... ASC/DESC
  • Can set SEPARATOR
  • As any aggregation function - it discards NULL values; plenty tricks on that.

(*) Support for Window Functions has been added in MySQL 8

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