爱站程序员基地Mysql 子查询、分组查询语句的灵活运用练习题
#子查询
CREATE TABLE emp(
empno INT,
ename VARCHAR(50),
job VARCHAR(50),
mgr INT,
hiredate DATE,
sal DECIMAL(7,2), – 薪资
comm DECIMAL(7,2), – 奖金
deptno INT
) ;
INSERT INTO emp VALUES(7369,‘SMITH’,‘CLERK’,7902,‘1980-12-17’,800,NULL,20);
INSERT INTO emp VALUES(7499,‘ALLEN’,‘SALESMAN’,7698,‘1981-02-20’,1600,300,30);
INSERT INTO emp VALUES(7521,‘WARD’,‘SALESMAN’,7698,‘1981-02-22’,1250,500,30);
INSERT INTO emp VALUES(7566,‘JONES’,‘MANAGER’,7839,‘1981-04-02’,2975,NULL,20);
INSERT INTO emp VALUES(7654,‘MARTIN’,‘SALESMAN’,7698,‘1981-09-28’,1250,1400,30);
INSERT INTO emp VALUES(7698,‘BLAKE’,‘MANAGER’,7839,‘1981-05-01’,2850,NULL,30);
INSERT INTO emp VALUES(7782,‘CLARK’,‘MANAGER’,7839,‘1981-06-09’,2450,NULL,10);
INSERT INTO emp VALUES(7788,‘SCOTT’,‘ANALYST’,7566,‘1987-04-19’,3000,NULL,20);
INSERT INTO emp VALUES(7839,‘KING’,‘PRESIDENT’,NULL,‘1981-11-17’,5000,NULL,10);
INSERT INTO emp VALUES(7844,‘TURNER’,‘SALESMAN’,7698,‘1981-09-08’,1500,0,30);
INSERT INTO emp VALUES(7876,‘ADAMS’,‘CLERK’,7788,‘1987-05-23’,1100,NULL,20);
INSERT INTO emp VALUES(7900,‘JAMES’,‘CLERK’,7698,‘1981-12-03’,950,NULL,30);
INSERT INTO emp VALUES(7902,‘FORD’,‘ANALYST’,7566,‘1981-12-03’,3000,NULL,20);
INSERT INTO emp VALUES(7934,‘MILLER’,‘CLERK’,7782,‘1982-01-23’,1300,NULL,10);
CREATE TABLE dept(
deptno INT,
dname VARCHAR(14),
loc VARCHAR(13)
);
INSERT INTO dept VALUES(10, ‘ACCOUNTING’, ‘NEW YORK’);
INSERT INTO dept VALUES(20, ‘RESEARCH’, ‘DALLAS’);
INSERT INTO dept VALUES(30, ‘SALES’, ‘CHICAGO’);
INSERT INTO dept VALUES(40, ‘OPERATIONS’, ‘BOSTON’);
SELECT * from emp ;
SELECT * from dept;
– 单行子查询(> < >= <= = <>)
– 查询出高于10号部门的平均工资的员工信息
select * from emp where sal>(select avg(sal) from emp where deptno=10);
– 多行子查询(in not in any all)
– 查询出比10号部门任何员工薪资高的员工信息
select * from emp where sal+comm>(select max(sal+comm) from emp where deptno=10)and deptno!=10;
– 多列子查询(实际使用较少)
– 和10号部门同名同工作的员工信息
select * from emp e where (ename,job)in (select ename,job from emp where deptno=10)and deptno!=10;
– select 后面接子查询
– 获取员工的名字和部门的名字
select ename,depto from emp;
select ename as 员工名字,(select dname from dept d where d.deptno=e.deptno)as 部门名称 from emp e;
– from 后面接子查询
– 查询emp表中经理信息
#1.查询出所有经理的ID
select distinct mgr from emp;
– 博客写的
select * from emp e,(select distinct mgr from emp) m where e.empno=m.mgr;
– 自己写的
select * from emp e,dept d where e.deptno=d.deptno and job=‘MANAGER’;
– where 后面接子查询
– 薪资高于10号部门平均工资的所有员工信息
select * from emp where sal>(select avg(sal) from emp where deptno=10);
– group by 后面接子查询
– 有哪些部门的平均工资高于30号部门的平均工资
select deptno 部门,avg(sal) 平均工资 from emp group by deptno having avg(sal)>(select avg(sal) from emp where deptno=30);
– 工资>JONES工资
select sal from emp where ename=‘jones’;
– 查询与SCOTT同一个部门的员工
select * from emp where deptno=(select deptno from emp where ename=‘SCOTT’);
– 工资高于30号部门所有人的员工信息
select * from emp where sal>(select max(sal) from emp where deptno=30);
– 查询工作和工资与MARTIN完全相同的员工信息
select * from emp where job=(select job from emp where ename=‘MARTIN’) and sal=(select sal from emp where ename=‘MARTIN’);
SELECT * FROM emp WHERE (job,sal) IN (SELECT job,sal FROM emp WHERE ename=‘MARTIN’);
– 有两个以上直接下属的员工信息
– 1.查出emp表中mgr信息
select mgr from emp;
– 2.分组统计mgr的信息
select mgr,COUNT() from emp group by mgr having count()>2;
select * from emp e1 where e1.empno in (select e2.mgr from emp e2 group by e2.mgr having count(*)>2);
– 查询员工编号为7788的员工名称,员工工资,部门名称,部门地址
select ename ,sal,dname,loc from emp e,dept d where e.deptno=d.deptno and empno=7788;
– SQL查询的综合案例
– 1. 查询出高于本部门平均工资的员工信息
– 先查询每个部门的平均工资
select deptno,avg(sal) from emp group by deptno;
select * from emp e1 where e1.sal>(select avg(e2.sal) from emp e2 where e1.deptno=e2.deptno group by e2.deptno);
select a.* from emp a,(select deptno,avg(sal) as sal from emp group by deptno) b where a.deptno=b.deptno and a.sal>b.sal
– 2. 列出达拉斯加工作的人中,比纽约平均工资高的人
select * from emp where deptno=(select deptno from dept where loc=‘DALLAS’) and sal>(select avg(sal) from emp where deptno=(select deptno from dept where loc=‘NEW YORK’));
– 3. 查询7369员工编号,姓名,经理编号和经理姓名
select e1.empno,e1.ename,e1.mgr,jingli.ename from emp e1 ,emp jingli where e1.mgr=jingli.empno and empno=7369;
– 4. 查询出各个部门薪水最高的员工所有信息
select * from emp e1 where e1.sal = (select MAX(sal) from emp e2 where e1.deptno = e2.deptno group by deptno);
面试题
– “`sql
CREATE TABLE test(
NAME CHAR(20),
kecheng CHAR(20),
fenshu CHAR(20)
);
INSERT INTO test VALUES(‘张三’,‘语文’,81),
(‘张三’,‘数学’,75),
(‘李四’,‘语文’,76),
(‘李四’,‘数学’,90),
(‘王五’,‘语文’,81),
(‘王五’,‘数学’,82);
– 请用一条Sql语句查处分数大于80的学生
select name,fenshu from test where fenshu>80;
