MySQL :: MySQL 8.0 Reference Manual

This page has moved or been replaced. The new page is located here: https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html Please update any bookmarks that point to the old page.

[dozo]

group_concat:複数のレコードを１行のcsvに置換

[oinume]

COUNT(*) is optimized to return very quickly if the SELECT retrieves from one table, no other columns are retrieved, and there is no WHERE clause.