查看表的字符集编码
show create table tbname;

查看系统默认字符集
SHOW VARIABLES LIKE 'character_set_database';

显示所有可用的字符集
SHOW CHARACTER SET;

修改系统默认字符集
①在  /etc/my.cnf  文件中的  [mysqld]  下添加：

②重启数据服务
systemctl restart mysqld

一、练习

创建表emp,表结构和需要插入的内容如下

任务要求

1、 select * from emp where deptno=30;

2、select empno,ename,deptno from emp where job='销售员';

3、select ename,sai,comm from emp where comm>sai;

4、select * from emp where comm>sai*0.6;

 

5、select * from emp where (deptno=10 and job='经理') or (deptno=20 and job='销售员');

 

6、select * from emp where (deptno=10 and job='经理') or (deptno=20 and job='销售员') or (job not in('经理','销售员') and sai>=20000);

  

7、select * from emp where comm is NULL or comm<1000;

 

8、select * from emp where ename like "___";

 

9、select * from emp where year(hiredate)=2000;

10、 select * from emp order by empno;

 

11、select * from emp order by sai desc,hiredate;

 

12、select deptno,round(avg(sai),2) from emp group by deptno;

 

13、select deptno,count(*) from emp group by deptno;

14、select job,max(sai),min(sai),count(*) from emp group by job;