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);
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’);
#查询数据
SELECT * FROM mydb.emp LIMIT 0,1000
SELECT * FROM mydb.dept LIMIT 0,1000
– 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>(SELECT MAX(sal) FROM emp where deptno=10) AND EMP.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 (e.ename,e.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 e.ename 员工名字,(select dname from dept where dept.deptno=e.deptno) 部门的名字 from emp e;
– from 后面接子查询
– 查询emp表中经理信息
select * from emp , dept where emp.deptno=dept.deptno and emp.job=‘MANAGER’;
SELECT * FROM EMP ,(SELECT DISTINCT job FROM emp WHERE JOB=‘MANAGER’) M WHERE EMP.JOB=M.JOB;
SELECT * FROM EMP ,(SELECT * FROM DEPT) M WHERE EMP.JOB=‘MANAGER’ AND M.DEPTNO=EMP.DEPTNO;
– 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 EMP.DEPTNO<>10 AND EMP.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 * from emp WHERE EMP.DEPTNO<>30 AND EMP.SAL>(select AVG(sal) from emp where deptno=30) ;
– 工资>JONES工资
SELECT * FROM EMP WHERE ENAME=‘JONES’ ;
– 查询与SCOTT同一个部门的员工
SELECT * FROM EMP,(SELECT * FROM EMP WHERE ENAME=‘SCOTT’) J WHERE EMP.JOB=J.JOB and emp.empno<>J.EMPNO;
– 工资高于30号部门所有人的员工信息
select * from emp WHERE EMP.DEPTNO<>30 AND EMP.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 ,(SELECT SAL,JOB FROM EMP WHERE ENAME=‘MARTIN’) M WHERE EMP.SAL=M.SAL AND EMP.JOB=M.JOB;
– 有两个以上直接下属的员工信息
SELECT *,COUNT(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 ENAME,SAL,DEPT.dname,DEPT.loc FROM EMP,DEPT WHERE EMP.empno=7788 AND EMP.deptno=DEPT.deptno;
/*
- 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
- 列出达拉斯加工作的人中,比纽约平均工资高的人
- 查询7369员工编号,姓名,经理编号和经理姓名
- 查询出各个部门薪水最高的员工所有信息
*/
– 1
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
SELECT * FROM EMP E1,(SELECT DEPTNO , AVG(SAL) SAL FROM EMP GROUP BY DEPTNO) E2 WHERE E1.deptno=E2.deptno AND E1.SAL>E2.SAL;
– 2
SELECT *FROM DEPT,EMP WHERE LOC=‘DALLAS’ AND EMP.deptno=DEPT.deptno AND SAL>(SELECT AVG(SAL) FROM DEPT,EMP WHERE LOC=‘NEW YORK’ AND EMP.deptno=DEPT.deptno);
– 3
SELECT *,ENAME 姓名,mgr 经理编号 FROM EMP WHERE emp.empno=7369;
– 4
SELECT *,MAX(SAL) 最高工资,DEPTNO 部门编号 FROM EMP GROUP BY DEPTNO;
SELECT * FROM EMP A ,(SELECT DEPTNO,MAX(SAL) SAL FROM EMP GROUP BY DEPTNO) B WHERE A.deptno=B.DEPTNO AND A.SAL=B.SAL;
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 * FROM TEST WHERE FENSHU>80;