- 子查詢
DROP DATABASE mydb2;

USE mydb1;

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');

-- 單行子查詢(> < >= <= = <>)
    -- 查詢出高於10號部門的平均工資的員工資訊 
    SELECT * FROM emp;
    SELECT * FROM dept;
    SELECT * FROM emp WHERE sal>(SELECT AVG(sal) FROM emp WHERE deptno= 10);
-- 多行子查詢(in  not in any all)
    -- 查詢出比10號部門任何員工薪資高的員工資訊
    SELECT * FROM emp WHERE sal>(SELECT MAX(sal) FROM emp WHERE deptno=10);
    SELECT * FROM emp WHERE sal>ALL(SELECT sal FROM emp WHERE deptno=10);
-- 多列子查詢(實際使用較少)
    -- 和10號部門同名同工作的員工資訊
    SELECT * FROM emp a WHERE (ename,job) IN (SELECT ename,job FROM emp WHERE deptno=10) AND deptno!=10;
-- select 後面接子查詢    
    -- 獲取員工的名字和部門的名字
    SELECT ename,dname FROM emp,dept WHERE emp.`deptno`=dept.`deptno` ORDER BY ename ASC;
-- from 後面接子查詢
    -- 查詢emp表中經理資訊
    SELECT * FROM emp WHERE job='MANAGER';
-- where 後面接子查詢    
    -- 薪資高於10號部門平均工資的所有員工資訊
    SELECT * FROM emp WHERE sal>(SELECT AVG(sal) FROM emp WHERE deptno= 10);
-- group by 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
    SELECT deptno FROM emp GROUP BY deptno HAVING AVG(sal)>(SELECT AVG(sal) FROM emp WHERE deptno=30);

-- 工資>JONES工資
-- 查詢與SCOTT同一個部門的員工
-- 工資高於30號部門所有人的員工資訊   -----自行完成喲！
-- 查詢工作和工資與MARTIN完全相同的員工資訊
SELECT * FROM emp WHERE (sal,job) IN(SELECT sal,job FROM emp WHERE ename='MARTIN') AND ename != 'MARTIN';
-- 有兩個以上直接下屬的員工資訊
-- 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   ---動動手美滋滋

-- SQL查詢的綜合案例
1. 查詢出高於本部門平均工資的員工資訊
SELECT * FROM emp;
SELECT * FROM dept;
SELECT deptno,AVG(sal) FROM emp GROUP BY deptno;
SELECT * FROM emp a WHERE sal>(SELECT AVG(sal) FROM emp b WHERE a.`deptno`=b.`deptno` GROUP BY b.`deptno`);
2. 列出達拉斯加工作的人中,比紐約平均工資高的人
SELECT * FROM emp WHERE sal >(SELECT AVG(sal) FROM emp WHERE deptno=(SELECT deptno FROM dept WHERE loc='NEW YORK'))
    AND deptno=(SELECT deptno FROM dept WHERE loc='DALLAS');
3. 查詢7369員工編號,姓名,經理編號和經理姓名
DESC emp;
SELECT e.empno,e.ename,mar.empno,mar.ename FROM emp e, emp mar WHERE e.empno=7369 AND e.deptno=mar.`deptno`AND mar.`job`='MANAGER' ;
4. 查詢出各個部門薪水最高的員工所有資訊
SELECT * FROM emp a WHERE sal=(SELECT MAX(sal) FROM emp b WHERE a.deptno=b.deptno GROUP BY deptno);

#### 面試題

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);

##請用一條Sql語句查出分數大於80的學生
SELECT DISTINCT NAME FROM test WHERE fenshu >80;
SELECT DISTINCT NAME FROM test WHERE NAME NOT IN(SELECT NAME FROM test WHERE fenshu<=80);