Results from queries can be retrieved into local variables

w将查询结果赋值给本地变量。

http://dev.mysql.com/doc/refman/5.7/en/stored-program-variables.html

Results from queries can be retrieved into local variables using SELECT ... INTO var_list or by opening a cursor and using FETCH ... INTO var_list. See Section 14.2.9.1, “SELECT ... INTO Syntax”, and Section 14.6.6, “Cursors”.