#插入 mysql> insert into emp values('zzx1','2002-03-09','2009-04-03','2001',3,22); Query OK, 1 row affected (0.00 sec) mysql> insert into emp values('ttx2','20023-04-10','2010-03-04','2002',4,23); ERROR 1292 (22007): Incorrect date value: '20023-04-10' for column 'birth' at row 1 mysql> insert into emp values('ttx2','2023-04-10','2010-03-04','2002',4,23); Query OK, 1 row affected (0.00 sec) mysql> select * from emp; +-------+------------+------------+---------+--------+------+ | ename | birth | hirdate | sal | deptno | age1 | +-------+------------+------------+---------+--------+------+ | zzx1 | 2000-01-01 | 2000-01-01 | 2000.00 | 1 | 21 | | zzx1 | 2002-03-09 | 2009-04-03 | 2001.00 | 3 | 22 | | ttx2 | 2023-04-10 | 2010-03-04 | 2002.00 | 4 | 23 | +-------+------------+------------+---------+--------+------+ 3 rows in set (0.00 sec) #更新 mysql> update emp set sal=4000 where ename='ttx2'; Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from emp; +-------+------------+------------+---------+--------+------+ | ename | birth | hirdate | sal | deptno | age1 | +-------+------------+------------+---------+--------+------+ | zzx1 | 2000-01-01 | 2000-01-01 | 2000.00 | 1 | 21 | | zzx1 | 2002-03-09 | 2009-04-03 | 2001.00 | 3 | 22 | | ttx2 | 2023-04-10 | 2010-03-04 | 4000.00 | 4 | 23 | +-------+------------+------------+---------+--------+------+ 3 rows in set (0.00 sec) mysql> select distinct deptno from emp; +--------+ | deptno | +--------+ | 1 | | 3 | | 4 | +--------+ 3 rows in set (0.01 sec) #查询 mysql> select * from emp where deptno=1; +-------+------------+------------+---------+--------+------+ | ename | birth | hirdate | sal | deptno | age1 | +-------+------------+------------+---------+--------+------+ | zzx1 | 2000-01-01 | 2000-01-01 | 2000.00 | 1 | 21 | +-------+------------+------------+---------+--------+------+ 1 row in set (0.00 sec) mysql> select * from emp where deptno=2; Empty set (0.00 sec) mysql> select * from emp where deptno=3; +-------+------------+------------+---------+--------+------+ | ename | birth | hirdate | sal | deptno | age1 | +-------+------------+------------+---------+--------+------+ | zzx1 | 2002-03-09 | 2009-04-03 | 2001.00 | 3 | 22 | +-------+------------+------------+---------+--------+------+ 1 row in set (0.00 sec) mysql> select * from emp order by sal; +-------+------------+------------+---------+--------+------+ | ename | birth | hirdate | sal | deptno | age1 | +-------+------------+------------+---------+--------+------+ | zzx1 | 2000-01-01 | 2000-01-01 | 2000.00 | 1 | 21 | | zzx1 | 2002-03-09 | 2009-04-03 | 2001.00 | 3 | 22 | | ttx2 | 2023-04-10 | 2010-03-04 | 4000.00 | 4 | 23 | +-------+------------+------------+---------+--------+------+ 3 rows in set (0.00 sec) mysql> select * from emp order by deptno; +-------+------------+------------+---------+--------+------+ | ename | birth | hirdate | sal | deptno | age1 | +-------+------------+------------+---------+--------+------+ | zzx1 | 2000-01-01 | 2000-01-01 | 2000.00 | 1 | 21 | | zzx1 | 2002-03-09 | 2009-04-03 | 2001.00 | 3 | 22 | | ttx2 | 2023-04-10 | 2010-03-04 | 4000.00 | 4 | 23 | +-------+------------+------------+---------+--------+------+ 3 rows in set (0.00 sec) #查询排序 mysql> select * from emp order by deptno,sal desc; +-------+------------+------------+---------+--------+------+ | ename | birth | hirdate | sal | deptno | age1 | +-------+------------+------------+---------+--------+------+ | zzx1 | 2000-01-01 | 2000-01-01 | 2000.00 | 1 | 21 | | zzx1 | 2002-03-09 | 2009-04-03 | 2001.00 | 3 | 22 | | ttx2 | 2023-04-10 | 2010-03-04 | 4000.00 | 4 | 23 | +-------+------------+------------+---------+--------+------+ 3 rows in set (0.00 sec) #分页查询 mysql> select * from emp order by sal limit 3; +-------+------------+------------+---------+--------+------+ | ename | birth | hirdate | sal | deptno | age1 | +-------+------------+------------+---------+--------+------+ | zzx1 | 2000-01-01 | 2000-01-01 | 2000.00 | 1 | 21 | | zzx1 | 2002-03-09 | 2009-04-03 | 2001.00 | 3 | 22 | | ttx2 | 2023-04-10 | 2010-03-04 | 4000.00 | 4 | 23 | +-------+------------+------------+---------+--------+------+ 3 rows in set (0.00 sec) mysql> select * from emp order by sal limit 1,3; +-------+------------+------------+---------+--------+------+ | ename | birth | hirdate | sal | deptno | age1 | +-------+------------+------------+---------+--------+------+ | zzx1 | 2002-03-09 | 2009-04-03 | 2001.00 | 3 | 22 | | ttx2 | 2023-04-10 | 2010-03-04 | 4000.00 | 4 | 23 | +-------+------------+------------+---------+--------+------+ 2 rows in set (0.00 sec) #查询表总数 mysql> select count(1) from emp; +----------+ | count(1) | +----------+ | 3 | +----------+ 1 row in set (0.00 sec) #针对emp表进行统计deptno的个数 mysql> select deptno,count(1) from emp group by deptno; +--------+----------+ | deptno | count(1) | +--------+----------+ | 1 | 1 | | 3 | 1 | | 4 | 1 | +--------+----------+ 3 rows in set (0.00 sec) #对ename排序并计算 mysql> select ename,count(1) from emp group by ename; +-------+----------+ | ename | count(1) | +-------+----------+ | ttx2 | 1 | | zzx1 | 2 | +-------+----------+ 2 rows in set (0.00 sec) #对sal排序并计算 mysql> select sal,count(1) from emp group by sal; +---------+----------+ | sal | count(1) | +---------+----------+ | 2000.00 | 1 | | 2001.00 | 1 | | 4000.00 | 1 | +---------+----------+ 3 rows in set (0.00 sec) #对age1排序并计算 mysql> select age1,count(1) from emp group by age1; +------+----------+ | age1 | count(1) | +------+----------+ | 21 | 1 | | 22 | 1 | | 23 | 1 | +------+----------+ 3 rows in set (0.01 sec) #查看emp表结构 mysql> desc emp; +---------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +---------+---------------+------+-----+---------+-------+ | ename | varchar(20) | YES | | NULL | | | birth | date | YES | | NULL | | | hirdate | date | YES | | NULL | | | sal | decimal(10,2) | YES | | NULL | | | deptno | int(2) | YES | | NULL | | | age1 | int(4) | YES | | NULL | | +---------+---------------+------+-----+---------+-------+ 6 rows in set (0.00 sec) #对birth列排序并计算 mysql> select birth,count(1) from emp group by birth; +------------+----------+ | birth | count(1) | +------------+----------+ | 2000-01-01 | 1 | | 2002-03-09 | 1 | | 2023-04-10 | 1 | +------------+----------+ 3 rows in set (0.00 sec) #对hirdate列排序并计算 mysql> select hirdate,count(1) from emp group by hirdate; +------------+----------+ | hirdate | count(1) | +------------+----------+ | 2000-01-01 | 1 | | 2009-04-03 | 1 | | 2010-03-04 | 1 | +------------+----------+ 3 rows in set (0.00 sec) #统计部门人数同时统计总人数 mysql> select deptno,count(1) from emp group by deptno with rollup; +--------+----------+ | deptno | count(1) | +--------+----------+ | 1 | 1 | | 3 | 1 | | 4 | 1 | | NULL | 3 | +--------+----------+ 4 rows in set (0.00 sec) #统计ename同时统计总人数 mysql> select ename,count(1) from emp group by ename with rollup; +-------+----------+ | ename | count(1) | +-------+----------+ | ttx2 | 1 | | zzx1 | 2 | | NULL | 3 | +-------+----------+ 3 rows in set (0.00 sec) #统计出生人数同时统计总人数 mysql> select birth,count(1) from emp group by birth with rollup; +------------+----------+ | birth | count(1) | +------------+----------+ | 2000-01-01 | 1 | | 2002-03-09 | 1 | | 2023-04-10 | 1 | | NULL | 3 | +------------+----------+ 4 rows in set (0.00 sec) #统计录用时间同时统计总人数 mysql> select hirdate,count(1) from emp group by hirdate with rollup; +------------+----------+ | hirdate | count(1) | +------------+----------+ | 2000-01-01 | 1 | | 2009-04-03 | 1 | | 2010-03-04 | 1 | | NULL | 3 | +------------+----------+ 4 rows in set (0.00 sec) #统计薪资数同时统计总人数 mysql> select sal,count(1) from emp group by sal with rollup; +---------+----------+ | sal | count(1) | +---------+----------+ | 2000.00 | 1 | | 2001.00 | 1 | | 4000.00 | 1 | | NULL | 3 | +---------+----------+ 4 rows in set (0.00 sec) #统计年龄同时统计总人数 mysql> select age1,count(1) from emp group by age1 with rollup; +------+----------+ | age1 | count(1) | +------+----------+ | 21 | 1 | | 22 | 1 | | 23 | 1 | | NULL | 3 | +------+----------+ 4 rows in set (0.00 sec) #统计部门大于0的部门 mysql> select deptno,count(1) from emp group by deptno having count(1)>0; +--------+----------+ | deptno | count(1) | +--------+----------+ | 1 | 1 | | 3 | 1 | | 4 | 1 | +--------+----------+ 3 rows in set (0.00 sec) #计算薪资总数、最高薪资、最低薪资 mysql> select sum(sal),max(sal),min(sal) from emp; +----------+----------+----------+ | sum(sal) | max(sal) | min(sal) | +----------+----------+----------+ | 8001.00 | 4000.00 | 2000.00 | +----------+----------+----------+ 1 row in set (0.00 sec) #联表查询 mysql> create table dept(deptno int(10),deptname varchar(20)); Query OK, 0 rows affected (0.01 sec) mysql> insert into dept values(1,'tech'); Query OK, 1 row affected (0.00 sec) mysql> insert into dept values(2,'sale'); Query OK, 1 row affected (0.00 sec) mysql> insert into dept values(3,'hr'); Query OK, 1 row affected (0.00 sec) mysql> select ename from emp where emp.deptno=emp.deptno; +-------+ | ename | +-------+ | zzx1 | | zzx1 | | ttx2 | +-------+ 3 rows in set (0.00 sec) #左连接查询 mysql> select ename,deptname from emp left join dept on emp.deptno=dept.deptno; +-------+----------+ | ename | deptname | +-------+----------+ | zzx1 | tech | | zzx1 | hr | | ttx2 | NULL | +-------+----------+ 3 rows in set (0.00 sec) #右连接查询 mysql> select ename,deptname from dept right join emp on dept.deptno=emp.deptno; +-------+----------+ | ename | deptname | +-------+----------+ | zzx1 | tech | | zzx1 | hr | | ttx2 | NULL | +-------+----------+ 3 rows in set (0.00 sec) mysql> select * from emp; +-------+------------+------------+---------+--------+------+ | ename | birth | hirdate | sal | deptno | age1 | +-------+------------+------------+---------+--------+------+ | zzx1 | 2000-01-01 | 2000-01-01 | 2000.00 | 1 | 21 | | zzx1 | 2002-03-09 | 2009-04-03 | 2001.00 | 3 | 22 | | ttx2 | 2023-04-10 | 2010-03-04 | 4000.00 | 4 | 23 | +-------+------------+------------+---------+--------+------+ 3 rows in set (0.00 sec) mysql> select * from dept; +--------+----------+ | deptno | deptname | +--------+----------+ | 1 | tech | | 2 | sale | | 3 | hr | +--------+----------+ 3 rows in set (0.01 sec) mysql> insert into dept values(4,'sl'); Query OK, 1 row affected (0.00 sec) mysql> insert into emp values('ssss','2019-01-01','2018-01-01',5000,2,24); Query OK, 1 row affected (0.00 sec) mysql> select * from dept; +--------+----------+ | deptno | deptname | +--------+----------+ | 1 | tech | | 2 | sale | | 3 | hr | | 4 | sl | +--------+----------+ 4 rows in set (0.00 sec) mysql> select * from emp; +-------+------------+------------+---------+--------+------+ | ename | birth | hirdate | sal | deptno | age1 | +-------+------------+------------+---------+--------+------+ | zzx1 | 2000-01-01 | 2000-01-01 | 2000.00 | 1 | 21 | | zzx1 | 2002-03-09 | 2009-04-03 | 2001.00 | 3 | 22 | | ttx2 | 2023-04-10 | 2010-03-04 | 4000.00 | 4 | 23 | | ssss | 2019-01-01 | 2018-01-01 | 5000.00 | 2 | 24 | +-------+------------+------------+---------+--------+------+ 4 rows in set (0.00 sec) mysql> select ename,deptname from emp left join dept on emp.deptno=dept.deptno; +-------+----------+ | ename | deptname | +-------+----------+ | zzx1 | tech | | ssss | sale | | zzx1 | hr | | ttx2 | sl | +-------+----------+ 4 rows in set (0.00 sec) mysql> select ename,deptname from dept right join emp on dept.deptno=emp.deptno; +-------+----------+ | ename | deptname | +-------+----------+ | zzx1 | tech | | ssss | sale | | zzx1 | hr | | ttx2 | sl | +-------+----------+ 4 rows in set (0.00 sec)