mysql -3练习（分组查询后再次筛选，顺逆序排序）

            /*插入表格*/
CREATE TABLE sanguo(
  empno   INT,
  ename   VARCHAR(20),
  job     VARCHAR(20),
  mgr      INT,
  hiredte   DATE,
  sal       DOUBLE,
  comm       DOUBLE,
  deptno     INT
  );
  SELECT * FROM sanguo;
  
  ALTER TABLE sanguo CHANGE COLUMN hiredte hiredate DATE;
  /*填入数据*/
  INSERT INTO sanguo VALUES(1001,‘甘宁‘,‘文员‘,1013,‘20001217‘,8000.00,NULL,20);
  INSERT INTO sanguo VALUES(1002,‘戴绮斯‘,‘销售员‘,1006,‘2001-02-20‘,16000.00,3000.00,30);
  INSERT INTO sanguo VALUES(1003,‘殷天正‘,‘销售员‘,1006,‘2001-02-22‘,12500.00,5000.00,30);
  INSERT INTO sanguo VALUES(1004,‘刘备‘,‘经理‘,1009,‘2001-04-02‘,29750.00,NULL,20);
  INSERT INTO sanguo VALUES(1005,‘谢逊‘,‘销售员‘,1006,‘2001-09-28‘,12500.00,14000.00,30);
  INSERT INTO sanguo VALUES(1006,‘关羽‘,‘经理‘,1009,‘2001-05-01‘,28500.00,NULL,30);
  INSERT INTO sanguo VALUES(1007,‘张飞‘,‘经理‘,1009,‘2001-09-01‘,24500.00,NULL,10);
  INSERT INTO sanguo VALUES(1008,‘诸葛亮‘,‘分析师‘,1004,‘2007-04-19‘,30000.00,NULL,20);
  INSERT INTO sanguo VALUES(1009,‘曾阿牛‘,‘董事长‘,NULL,‘2001-11-17‘,50000.00,NULL,10);
  INSERT INTO sanguo VALUES(1010,‘韦一笑‘,‘销售员‘,1006,‘2001-09-08‘,15000.00,0.00,30);
  INSERT INTO sanguo VALUES(1011,‘周泰‘,‘文员‘,1008,‘2007-05-23‘,11000.00,NULL,20);
  INSERT INTO sanguo VALUES(1012,‘程普‘,‘文员‘,1006,‘2001-12-03‘,9500.00,NULL,30);
  INSERT INTO sanguo VALUES(1013,‘庞统‘,‘分析师‘,1004,‘2001-12-03‘,30000.00,NULL,20);
  INSERT INTO sanguo VALUES(1014,‘黄盖‘,‘文员‘,1007,‘2002-01-23‘,13000.00,NULL,10);
  INSERT INTO sanguo VALUES(1015,‘张三‘,‘保洁员‘,1001,‘2013-05-01‘,80000.00,50000.00,50);
  
  /*查询所有部门编号为30的员工*/
  SELECT * FROM sanguo WHERE deptno = 30;
  /*查询所有职位为销售员的员工的编号，姓名，部门编号*/
  SELECT empno,ename,deptno FROM sanguo WHERE job = ‘销售员‘;
  /*查询所有奖金大于工资的员工*/
  SELECT * FROM sanguo WHERE comm > sal ;
  /*查询所有奖金大于工资60%的员工*/
  SELECT * FROM sanguo WHERE comm > (0.6*sal);
  /*查询所有部门编号为10同时是经理或者部门编号为20同时是销售员的员工*/
  SELECT * FROM sanguo WHERE ( deptno = 10 AND job = ‘经理‘) OR (deptno = 20 AND job = ‘销售员‘ );
  /*查询所有部门编号为10同时是经理或者部门编号为20同时是销售员或奖金大于20000的员工*/
  SELECT * FROM sanguo WHERE ( deptno = 10 AND job = ‘经理‘) OR (deptno = 20 AND job = ‘销售员‘ )OR(comm >= 20000);
   /*查询所有没有奖金或奖金小于1000的员工*/
  SELECT ename FROM sanguo WHERE comm IS NULL OR comm < 1000;
   /*查询所有名字是三个字的员工*/
  SELECT ename FROM sanguo WHERE ename LIKE ‘___‘;
   /*查询所有2000年加入公司的员工*/
  SELECT * FROM sanguo WHERE hiredate LIKE ‘2000%‘;
    /*查询所有员工详细信息，用编号升序排序*/
  SELECT * FROM sanguo ORDER BY empno ASC;
   /*查询所有员工详细信息，用工资降序排序，如果工资相同使用入职日期升序排序*/
  SELECT * FROM sanguo ORDER BY sal DESC,hiredate ASC;
   /*查询姓周的两个名字的员工。*/
  SELECT * FROM sanguo WHERE ename LIKE ‘周_‘;
  /*查询所有姓张的员工。*/
  SELECT * FROM sanguo WHERE ename LIKE ‘张%‘;
  /*查询该部门有多少个岗位，每个岗位有多少人。*/
  SELECT job,COUNT(*) FROM sanguo GROUP BY job;
  /*查询哪个岗位中人数大于3。*/
  SELECT job FROM sanguo GROUP BY job HAVING COUNT(*)>3;