多表子查询练习

– 单行子查询(> < >= <= = <>)
– 查询出高于10号部门的平均工资的员工信息

– 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
– 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 后面接子查询
– 获取员工的名字和部门的名字
– from 后面接子查询
– 查询emp表中经理信息
– 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
– 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

– 工资>JONES工资
– 查询与SCOTT同一个部门的员工
– 工资高于30号部门所有人的员工信息
– 查询工作和工资与MARTIN完全相同的员工信息
– 有两个以上直接下属的员工信息
– 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

• 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
2. 列出达拉斯加工作的人中,比纽约平均工资高的人
3. 查询7369员工编号,姓名,经理编号和经理姓名
4. 查询出各个部门薪水最高的员工所有信息
   

CREATE TABLE emp(
	empno		INT,
	ename		VARCHAR(50),
	job		VARCHAR(50),
	mgr		INT,
	hiredate	DATE,
	sal		DECIMAL(7,2),
	comm		DECIMAL(7,2),
	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);

SELECT * FROM emp
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 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 avg(sal) from emp where deptno>10;
	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 sal FROM emp WHERE deptno = 10;
	SELECT *FROM emp WHERE sal >ANY(SELECT sal 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 ename,job from emp where deptno=10;
	SELECT * FROM emp 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,deptno FROM emp;
	
# from 后面接子查询
    # 查询emp表中经理信息
	SELECT DISTINCT mgr  FROM emp;
# 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 avg(sal) from emp where deptno>10;
	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 avg(sal)from emp where deptno=30;
	#select deptno ,avg(sal) from emp group by deptno;
	SELECT deptno ,AVG(sal) 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';
SELECT *FROM emp WHERE sal>(SELECT sal FROM emp WHERE ename='JONES');	
# 查询与SCOTT同一个部门的员工
SELECT deptno FROM emp WHERE ename='SCOTT';
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 sal FROM emp WHERE deptno=30;
SELECT *FROM emp WHERE sal> ANY(SELECT 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 job,sal FROM emp WHERE ename='MARTIN';
SELECT * FROM emp WHERE(job,sal)IN(SELECT job,sal FROM emp WHERE ename='MARTIN')AND empno!=7654;
# 有两个以上直接下属的员工信息
SELECT * FROM emp WHERE mgr IN(SELECT mgr FROM emp GROUP BY mgr HAVING COUNT(mgr)>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 sal,dname,loc FROM emp,dept WHERE emp.`deptno`=dept.`deptno` AND mgr='7788'

# SQL查询的综合案例
#. 查询出高于本部门平均工资的员工信息
SELECT * FROM emp e1 WHERE e1.sal > 
(SELECT AVG(e2.sal) FROM emp e2 WHERE e1.deptno=e2.deptno  GROUP BY e2.deptno);

#. 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'))
#. 查询7369员工编号,姓名,经理编号和经理姓名
SELECT e.empno,e.ename,d.deptno,d.dname FROM emp e,dept d WHERE e.`deptno` = d.`deptno` AND empno='7369'
#. 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);