1、判断两个时间的时间差
-- 秒
TIMESTAMPDIFF(SECOND ,time1,time2);
-- 分
TIMESTAMPDIFF(MINUTE ,time1,time2);
-- 时
TIMESTAMPDIFF(HOUR ,time1,time2);
-- 天
TIMESTAMPDIFF(DAY ,time1,time2);
-- 月
TIMESTAMPDIFF(MONTH ,time1,time2);
-- 年
TIMESTAMPDIFF(YEAR ,time1,time2);
2、将每一行的 id拼接起来
GROUP_CONCAT(id SEPARATOR ';')
SELECT cp_id,GROUP_CONCAT(id SEPARATOR ";") AS id FROM z_01 GROUP BY cp_id;
表:z_01
3、将字符串中的 某个字符或字符串 替换 成指定的字符串
UPDATE z_02 SET cp_id=REPLACE(cp_id,";","");
表:z_02 处理前 表:z_02处理后
4、截取字符串
SELECT SUBSTR(cp_id ,5, 4) AS cp_id FROM z_03;
从第5位截取,截取长度为4;
表:z_03 查询结果