Redhat7 安装mariadb（原mysql）
安装：
# yum install mariadb mariadb-server
启动并开机启动：
# systemctl start mariadb
# systemctl enable mariadb
此时mysql的root密码为空
# mysql –u root
-
user mysql;
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update user set password=password(‘123456’) where user=root;
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flush privileges;
-
quit
开防火墙：
# firewall-cmd –permanent –add-service=mysql
# firewall-cmd --reload
# vi /etc/my.cnf （mysqld下）
Skip-networking= 1 （关闭远程通过ip进行连接，默认是允许的）
:wq
link 模糊查询
link ‘%a%’ 中间含字母a的
link ‘_a%’ 以a结尾的
link ‘%a_’ 以a开头的
语句示例（注意区分函数、字段、表名）：
select * from worker where sal >= 2500;
select * from worker where sal != 2500;
select * from worker where deptno in(2,4);
select * from worker where sal between 1500 and 2500;
select avg(sal) from worker;
select max(sal) from worker;
select min(sal) from worker;
select * from worker order by deptno; （升序排列）
select * from worker order by deptno desc; （降序排列）
select deptno,max(sal) from worker group by deptno;
create table test as select * from worker;
内连接：
select student,sno,student.sname,coll.cname from student join coll onstudent.cno=coll.con;
左外连接：
select s.sno,s.sname,c.cnamefrom student as s left join coll as c on s.cno=c.cno;
右连接：
select s.sno,s.sname,c.cnamefrom coll as c right join student as s on s.cno=c.cno;
本文转自linux博客51CTO博客，原文链接http://blog.51cto.com/yangzhiming/1721717如需转载请自行联系原作者
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