MYSQL多表子查詢練習
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);
INSERT INTO emp VALUES(7981,‘MILLER’,‘CLERK’,7788,‘1992-01-23’,2600,500,20);
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’);
DESC SELECT dname FROM dept WHERE deptno=10;
– 單行子查詢(> < >= <= = <>)
– 查詢出高於10號部門的平均工資的員工資訊
1.查詢出10號部門的平均工資
SELECT AVG(sal) FROM emp WHERE deptno = 10;
2.查詢出高於10號部門平均工資的員工資訊
SELECT * FROM emp WHERE sal > (SELECT AVG(sal) FROM emp WHERE deptno = 10);
– 多行子查詢(in not in any all) >any >all
– 查詢出比10號部門任何員工薪資高的員工資訊
1. 查詢出10號部門的所有工資資訊
SELECT sal FROM emp WHERE deptno=10;
2.得出結果
SELECT * FROM emp WHERE sal >any(SELECT sal FROM emp WHERE deptno=10);
– 多列子查詢(實際使用較少) in
– 和10號部門同名同工作的員工資訊
1.查出10號部門員工名字和工作資訊
SELECT ename,job FROM emp WHERE deptno=10;
2. 得出結果:
SELECT * FROM emp WHERE (ename,job) IN (SELECT ename,job FROM emp WHERE deptno=10) AND deptno!=10;
– Select接子查詢
– 獲取員工的名字和部門的名字
1.查出員工的名字和部門編號資訊
SELECT ename,deptno FROM emp;
2.得出結果
SELECT ename,(SELECT dname FROM dept WHERE dept.deptno=emp.deptno) FROM emp;
– from後面接子查詢
– 查詢emp表中經理資訊
1.查詢出所有經理的ID
SELECT DISTINCT mgr FROM emp;
2. 查出經理的資訊,只要id在第一步的查詢結果中就可以了
SELECT * FROM emp,(SELECT DISTINCT mgr FROM emp) mgrs WHERE emp.empno = mgrs.mgr;
– where 接子查詢
– 薪資高於10號部門平均工資的所有員工資訊
1.查詢出10號部門的平均工資
SELECT AVG(sal) FROM emp WHERE deptno=10;
2.得出結果:
SELECT * FROM emp WHERE sal > (SELECT AVG(sal) FROM emp WHERE deptno=10);
– having後面接子查詢
– 有哪些部門的平均工資高於30號部門的平均工資
1.30號部門的平均工資
SELECT AVG(sal) FROM emp WHERE deptno=30;
2. 統計所有部門的平均工資
SELECT deptno,AVG(sal) FROM emp GROUP BY deptno ;
3. 得出最終的結果
SELECT deptno,AVG(sal) FROM emp GROUP BY deptno HAVING AVG(sal) > (SELECT AVG(sal) FROM emp WHERE deptno=30);
– 工資>JONES工資的員工資訊
1.查處JONES的工資資訊
SELECT sal FROM emp WHERE ename=‘JONES’;
2.得出結果
SELECT * FROM emp WHERE sal > (SELECT sal FROM emp WHERE ename=‘JONES’);
– 查詢與SCOTT同一個部門的員工
1.查處SCOTT的部門編號
SELECT deptno FROM emp WHERE ename = ‘SCOTT’;
2.得出結果
SELECT * FROM emp WHERE deptno = (SELECT deptno FROM emp WHERE ename = ‘SCOTT’);
– 工資高於30號部門所有人的員工資訊
1.得出30號部門的最大工資
SELECT MAX(sal) FROM emp WHERE deptno = 30;
2.得出結果
SELECT * FROM emp WHERE sal > (SELECT MAX(sal) FROM emp WHERE deptno = 30);
– 查詢工作和工資與MARTIN完全相同的員工資訊
1.查處MARTIN的工作和工資
SELECT job,sal FROM emp WHERE ename=‘MARTIN’;
2.得出結果
SELECT * FROM emp WHERE (job,sal) IN (SELECT job,sal FROM emp WHERE ename=‘MARTIN’);
– 有兩個以上直接下屬的員工資訊
1.查出emp表中mgr資訊
SELECT mgr FROM emp;
2.分組統計mgr的資訊
SELECT mgr,COUNT() FROM emp GROUP BY mgr HAVING COUNT()>2;
3.得出結果
SELECT * FROM emp e1 WHERE e1.empno IN (SELECT e2.mgr FROM emp e2 GROUP BY e2.mgr HAVING COUNT(*)>2);
– 查詢員工編號為7788的員工名稱,員工工資,部門名稱,部門地址
1.將員工表和部門錶鏈接起來
SELECT * FROM emp ,dept WHERE emp.deptno = dept.deptno;
2.得出ID為7788的所有資訊
SELECT * FROM emp ,dept WHERE emp.deptno = dept.deptno AND empno=7788;
3.只顯示其中的需要的資訊
SELECT ename,sal ,dname, loc FROM emp ,dept WHERE emp.deptno = dept.deptno AND empno=7788;
– 1. 查詢出高於本部門平均工資的員工資訊
1. 分組統計每個部門的平均工資
SELECT deptno,AVG(sal) FROM emp GROUP BY deptno;
2. 得出相應的結果
SELECT * FROM emp e1 WHERE e1.sal > (SELECT AVG(e2.sal) FROM emp e2 WHERE e1.deptno=e2.deptno GROUP BY e2.deptno);
– 1. 列出達拉斯加工作的人中,比紐約平均工資高的人
0. 查處DALLAS 的部門編號
SELECT deptno FROM dept WHERE loc=‘DALLAS’;
1.查處達拉斯工作的人的資訊
SELECT * FROM emp WHERE deptno = (SELECT deptno FROM dept WHERE loc=‘DALLAS’);
2. 查處紐約的部門編號
SELECT deptno FROM dept WHERE loc=‘NEW YORK’;
3. 查村紐約平均工資
SELECT AVG(sal) FROM emp WHERE deptno = (SELECT deptno FROM dept WHERE loc=‘NEW YORK’);
4.得出結果:
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’));
– 2. 查詢7369員工編號,姓名,經理編號和經理姓名
SELECT e1.empno,e1.ename,e1.mgr,mgrtable.ename FROM emp e1,emp mgrtable WHERE e1.mgr = mgrtable.empno;
– 3. 查詢出各個部門薪水最高的員工所有資訊
1.分組統計每個部門員工最高的薪資是多少
SELECT MAX(sal),deptno FROM emp GROUP BY deptno;
2.算出結果
SELECT * FROM emp e1 WHERE e1.sal = (SELECT MAX(sal) FROM emp e2 WHERE e1.deptno = e2.deptno GROUP BY deptno);
CREATE TABLE test(
NAME CHAR(20),
kecheng CHAR(20),
fenshu CHAR(20)
);
INSERT INTO test VALUES
(‘張三’,‘語文’,81),
(‘張三’,‘數學’,75),
(‘李四’,‘語文’,76),
(‘李四’,‘數學’,90),
(‘王五’,‘語文’,81),
(‘王五’,‘數學’,82);
SELECT NAME FROM test WHERE fenshu < 80 ;
SELECT NAME FROM test WHERE NAME NOT IN(SELECT NAME FROM test WHERE fenshu < 80 );