MySQL Functions 函数

Window functions 窗口函数

A window function performs an aggregate-like operation on a set of query rows. However, whereas an aggregate operation groups query rows into a single result row, a window function produces a result for each query row:

• The row for which function evaluation occurs is called the current row.
• The query rows related to the current row over which function evaluation occurs comprise the window for the current row.

与聚合函数不同，聚合函数在所有查询后返回一个结果，窗口函数为每个查询创建一个结果。

Exercises

• rank-scores (DENCE_RANK() function)