mysql 存储过程时间月份减法

declare startTime VARCHAR(19) default '2014-00-00 00:00:00';
declare tempTime VARCHAR(19) default NOW();
declare endTime VARCHAR(19) default DATE_SUB(tempTime,INTERVAL '3' MONTH); --  后退三个月时间

DECLARE MONTHSTR VARCHAR(7) default SUBSTR(endTime,1,7);
set endTime=CONCAT(MONTHSTR,'-00 00:00:00');


SELECT startTime  as startTime,endTime AS endTime;