在mysql里怎样自定义函数?CREATE FUNCTION 函数名称(参数列表) RETURNS 返回值类型 函数体如:CREATE FUNCTION IF EXIST deleteById(uid SMALLINT UNSIGNED) RETURNS VARCHAR(20) BEGINDELETE FROM son WHERE id = uidRETURN (SELECT COUNT(id) FROM son)END调用如:select 函数名(参数列表)