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
or by opening a cursor and using var_list
FETCH ... INTO
. See Section 14.2.9.1, “SELECT ... INTO Syntax”, and Section 14.6.6, “Cursors”.var_list