mysql 常用函數(shù)聚合函數(shù)以及md5加密算法
5.mysql函數(shù)
常用函數(shù)
--絕對值
select abs(-8);
--向上取整
select ceiling(9.4);
--向下取整
select floor(9.4);
--隨機數(shù)
select rand();
--判斷正負數(shù)
select sign(-1);
--字符串長度
select char_length('lllll');
--拼接字符串
select concat('w','s');
--字符串替換
select insert('woaibiancheng',1,4,'llll');
--轉(zhuǎn)換大小寫
select lower('SS');
select upper('hh');
--第一次出現(xiàn)的字串的索引
select replace('sss','ss','ww');
--返回指定的字符串 從第幾個開始截取幾個
select substr('ssssss',4,6);
--獲取當前時間
select current_date();
select now();
select localtime();
select current();
select year(now());
select month(now());
? ? ? ......
聚合函數(shù)
函數(shù)名稱描述sum()總和avg()平均值max()最大值min()最小值count()計數(shù)select count(*) from student;
select count(1) from student;
select count(name) from student;
select sum(name) from student;
select avg(name) from student;
select min(name) from student;
select max(name) from student;
數(shù)據(jù)庫級別的md5加密算法
--建表
mysql> create table testmd5(
`id` int(4) not null,
`name` varchar(20) not null,
`pwd` varchar(50) not null,
primary key(`id`)
)engine=innodb default charset=utf8;
--插入數(shù)據(jù)
insert into testmd5 values(1,'zhangsan','123123'),(2,'lisi','123123'),(3,'wangwu','123123');
--更新密碼為MD5
update testmd5 set pwd=md5(pwd);
--插入密碼為MD5
insert into testmd5 values(4,'xixi',md5('123123'));
原文：https://www.dianjilingqu.com/445666.html
