重庆论坛建站模板,电商运营培训大概多少学费,做书网站,百度推广后台登录首页目录 一#xff0c;单表查询
二#xff0c;多表查询
三#xff0c;自连接
四#xff0c;子查询
1#xff0c;单行查询
2#xff0c;多行查询
3#xff0c;多列查询
4#xff0c;在from子句中使用子查询
5#xff0c;合并查询
1#xff0c;union
2#xff… 目录 一单表查询
二多表查询
三自连接
四子查询
1单行查询
2多行查询
3多列查询
4在from子句中使用子查询
5合并查询
1union
2union all 一单表查询
前面mysql表的增删查改都是对一张表进行查询
--查询工资高于500或岗位为MANAGER的雇员同时还要满足他们的姓名首字母为大写的J
mysql select * from emp where (sal500 or job MANAGER) and ename likej%;
--------------------------------------------------------------------------
| empno | ename | job | mgr | hiredate | sal | comm | deptno |
--------------------------------------------------------------------------
| 007566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 |
| 007900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950.00 | NULL | 30 |
--------------------------------------------------------------------------
2 rows in set (0.00 sec)--按照部门号升序而雇员的工资降序排序
mysql select * from emp order by deptno, sal desc;
--------------------------------------------------------------------------------
| empno | ename | job | mgr | hiredate | sal | comm | deptno |
--------------------------------------------------------------------------------
| 007839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL | 10 |
| 007782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450.00 | NULL | 10 |
| 007934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300.00 | NULL | 10 |
| 007788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000.00 | NULL | 20 |
| 007902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL | 20 |
| 007566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 |
| 007876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100.00 | NULL | 20 |
| 007369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800.00 | NULL | 20 |
| 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 |
| 007499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600.00 | 300.00 | 30 |
| 007844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500.00 | 0.00 | 30 |
| 007521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250.00 | 500.00 | 30 |
| 007654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 | 30 |
| 007900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950.00 | NULL | 30 |
--------------------------------------------------------------------------------
14 rows in set (0.00 sec)--使用年薪进行降序排序显示工资最高的员工的名字和工作岗位
mysql select * from emp order by deptno, sal desc;
--------------------------------------------------------------------------------
| empno | ename | job | mgr | hiredate | sal | comm | deptno |
--------------------------------------------------------------------------------
| 007839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL | 10 |
| 007782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450.00 | NULL | 10 |
| 007934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300.00 | NULL | 10 |
| 007788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000.00 | NULL | 20 |
| 007902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL | 20 |
| 007566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 |
| 007876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100.00 | NULL | 20 |
| 007369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800.00 | NULL | 20 |
| 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 |
| 007499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600.00 | 300.00 | 30 |
| 007844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500.00 | 0.00 | 30 |
| 007521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250.00 | 500.00 | 30 |
| 007654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 | 30 |
| 007900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950.00 | NULL | 30 |
--------------------------------------------------------------------------------
14 rows in set (0.00 sec)--使用年薪进行降序排序
mysql select ename, sal*12ifnull(comm,0) as 年薪 from emp order by 年薪 desc;
------------------
| ename | 年薪 |
------------------
| KING | 60000.00 |
| SCOTT | 36000.00 |
| FORD | 36000.00 |
| JONES | 35700.00 |
| BLAKE | 34200.00 |
| CLARK | 29400.00 |
| ALLEN | 19500.00 |
| TURNER | 18000.00 |
| MARTIN | 16400.00 |
| MILLER | 15600.00 |
| WARD | 15500.00 |
| ADAMS | 13200.00 |
| JAMES | 11400.00 |
| SMITH | 9600.00 |
------------------
14 rows in set (0.00 sec)--显示工资最高的员工的名字和工作岗位
mysql select ename, job from emp where sal (select max(sal) from emp);
------------------
| ename | job |
------------------
| KING | PRESIDENT |
------------------
1 row in set (0.00 sec)--显示工资高于平均工资的员工信息
mysql select ename, sal from emp where sal (select avg(sal) from emp);
----------------
| ename | sal |
----------------
| JONES | 2975.00 |
| BLAKE | 2850.00 |
| CLARK | 2450.00 |
| SCOTT | 3000.00 |
| KING | 5000.00 |
| FORD | 3000.00 |
----------------
6 rows in set (0.00 sec)--显示每个部门的平均工资和最高工资
mysql select deptno, format(avg(sal), 2), max(sal) from emp group by deptno;
---------------------------------------
| deptno | format(avg(sal), 2) | max(sal) |
---------------------------------------
| 10 | 2,916.67 | 5000.00 |
| 20 | 2,175.00 | 3000.00 |
| 30 | 1,566.67 | 2850.00 |
---------------------------------------
3 rows in set (0.00 sec)--显示平均工资低于2000的部门号和它的平均工资
mysql select deptno, avg(sal) as avg_sal from emp group by deptno having avg_sal 2000;
---------------------
| deptno | avg_sal |
---------------------
| 30 | 1566.666667 |
---------------------
1 row in set (0.00 sec)--显示每种岗位的雇员总数平均工资
mysql select job, count(*), format(avg(sal),2) from emp group by job;
-----------------------------------------
| job | count(*) | format(avg(sal),2) |
-----------------------------------------
| ANALYST | 2 | 3,000.00 |
| CLERK | 4 | 1,037.50 |
| MANAGER | 3 | 2,758.33 |
| PRESIDENT | 1 | 5,000.00 |
| SALESMAN | 4 | 1,400.00 |
-----------------------------------------
5 rows in set (0.00 sec)
二多表查询
实际开发中往往数据来自不同的表所以需要多表查询。
mysql select * from emp, dept;
--------------------------------------------------------------------------------------------------------------
| empno | ename | job | mgr | hiredate | sal | comm | deptno | deptno | dname | loc |
--------------------------------------------------------------------------------------------------------------
| 007369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800.00 | NULL | 20 | 10 | ACCOUNTING | NEW YORK |
| 007369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800.00 | NULL | 20 | 20 | RESEARCH | DALLAS |
| 007369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800.00 | NULL | 20 | 30 | SALES | CHICAGO |
| 007369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800.00 | NULL | 20 | 40 | OPERATIONS | BOSTON |
| 007499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600.00 | 300.00 | 30 | 10 | ACCOUNTING | NEW YORK |
| 007499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600.00 | 300.00 | 30 | 20 | RESEARCH | DALLAS |
| 007499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600.00 | 300.00 | 30 | 30 | SALES | CHICAGO |
| 007499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600.00 | 300.00 | 30 | 40 | OPERATIONS | BOSTON |
| 007521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250.00 | 500.00 | 30 | 10 | ACCOUNTING | NEW YORK |
| 007521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250.00 | 500.00 | 30 | 20 | RESEARCH | DALLAS |
| 007521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250.00 | 500.00 | 30 | 30 | SALES | CHICAGO |
| 007521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250.00 | 500.00 | 30 | 40 | OPERATIONS | BOSTON |
| 007566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 | 10 | ACCOUNTING | NEW YORK |
| 007566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 | 20 | RESEARCH | DALLAS |
| 007566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 | 30 | SALES | CHICAGO |
| 007566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 | 40 | OPERATIONS | BOSTON |
| 007654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 | 30 | 10 | ACCOUNTING | NEW YORK |
| 007654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 | 30 | 20 | RESEARCH | DALLAS |
| 007654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 | 30 | 30 | SALES | CHICAGO |
| 007654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 | 30 | 40 | OPERATIONS | BOSTON |
| 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 | 10 | ACCOUNTING | NEW YORK |
| 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 | 20 | RESEARCH | DALLAS |
| 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 | 30 | SALES | CHICAGO |
| 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 | 40 | OPERATIONS | BOSTON |
| 007782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450.00 | NULL | 10 | 10 | ACCOUNTING | NEW YORK |
| 007782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450.00 | NULL | 10 | 20 | RESEARCH | DALLAS |
| 007782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450.00 | NULL | 10 | 30 | SALES | CHICAGO |
| 007782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450.00 | NULL | 10 | 40 | OPERATIONS | BOSTON |
| 007788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000.00 | NULL | 20 | 10 | ACCOUNTING | NEW YORK |
| 007788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000.00 | NULL | 20 | 20 | RESEARCH | DALLAS |
| 007788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000.00 | NULL | 20 | 30 | SALES | CHICAGO |
| 007788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000.00 | NULL | 20 | 40 | OPERATIONS | BOSTON |
| 007839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL | 10 | 10 | ACCOUNTING | NEW YORK |
| 007839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL | 10 | 20 | RESEARCH | DALLAS |
| 007839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL | 10 | 30 | SALES | CHICAGO |
| 007839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL | 10 | 40 | OPERATIONS | BOSTON |
| 007844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500.00 | 0.00 | 30 | 10 | ACCOUNTING | NEW YORK |
| 007844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500.00 | 0.00 | 30 | 20 | RESEARCH | DALLAS |
| 007844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500.00 | 0.00 | 30 | 30 | SALES | CHICAGO |
| 007844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500.00 | 0.00 | 30 | 40 | OPERATIONS | BOSTON |
| 007876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100.00 | NULL | 20 | 10 | ACCOUNTING | NEW YORK |
| 007876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100.00 | NULL | 20 | 20 | RESEARCH | DALLAS |
| 007876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100.00 | NULL | 20 | 30 | SALES | CHICAGO |
| 007876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100.00 | NULL | 20 | 40 | OPERATIONS | BOSTON |
| 007900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950.00 | NULL | 30 | 10 | ACCOUNTING | NEW YORK |
| 007900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950.00 | NULL | 30 | 20 | RESEARCH | DALLAS |
| 007900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950.00 | NULL | 30 | 30 | SALES | CHICAGO |
| 007900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950.00 | NULL | 30 | 40 | OPERATIONS | BOSTON |
| 007902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL | 20 | 10 | ACCOUNTING | NEW YORK |
| 007902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL | 20 | 20 | RESEARCH | DALLAS |
| 007902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL | 20 | 30 | SALES | CHICAGO |
| 007902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL | 20 | 40 | OPERATIONS | BOSTON |
| 007934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300.00 | NULL | 10 | 10 | ACCOUNTING | NEW YORK |
| 007934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300.00 | NULL | 10 | 20 | RESEARCH | DALLAS |
| 007934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300.00 | NULL | 10 | 30 | SALES | CHICAGO |
| 007934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300.00 | NULL | 10 | 40 | OPERATIONS | BOSTON |
--------------------------------------------------------------------------------------------------------------
56 rows in set (0.00 sec)--显示雇员名、雇员工资以及所在部门的名字因为上面的数据来自EMP和DEPT表因此要联合查询
mysql select * from emp, dept where emp.deptno dept.deptno;
--------------------------------------------------------------------------------------------------------------
| empno | ename | job | mgr | hiredate | sal | comm | deptno | deptno | dname | loc |
--------------------------------------------------------------------------------------------------------------
| 007369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800.00 | NULL | 20 | 20 | RESEARCH | DALLAS |
| 007499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600.00 | 300.00 | 30 | 30 | SALES | CHICAGO |
| 007521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250.00 | 500.00 | 30 | 30 | SALES | CHICAGO |
| 007566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 | 20 | RESEARCH | DALLAS |
| 007654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 | 30 | 30 | SALES | CHICAGO |
| 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 | 30 | SALES | CHICAGO |
| 007782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450.00 | NULL | 10 | 10 | ACCOUNTING | NEW YORK |
| 007788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000.00 | NULL | 20 | 20 | RESEARCH | DALLAS |
| 007839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL | 10 | 10 | ACCOUNTING | NEW YORK |
| 007844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500.00 | 0.00 | 30 | 30 | SALES | CHICAGO |
| 007876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100.00 | NULL | 20 | 20 | RESEARCH | DALLAS |
| 007900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950.00 | NULL | 30 | 30 | SALES | CHICAGO |
| 007902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL | 20 | 20 | RESEARCH | DALLAS |
| 007934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300.00 | NULL | 10 | 10 | ACCOUNTING | NEW YORK |
--------------------------------------------------------------------------------------------------------------
14 rows in set (0.00 sec)--只显示雇员名、雇员工资、所在部门名、部门编号的字段
mysql select emp.ename,emp.sal,dept.dname,dept.deptno from emp, dept where emp.deptno dept.deptno;
-------------------------------------
| ename | sal | dname | deptno |
-------------------------------------
| SMITH | 800.00 | RESEARCH | 20 |
| ALLEN | 1600.00 | SALES | 30 |
| WARD | 1250.00 | SALES | 30 |
| JONES | 2975.00 | RESEARCH | 20 |
| MARTIN | 1250.00 | SALES | 30 |
| BLAKE | 2850.00 | SALES | 30 |
| CLARK | 2450.00 | ACCOUNTING | 10 |
| SCOTT | 3000.00 | RESEARCH | 20 |
| KING | 5000.00 | ACCOUNTING | 10 |
| TURNER | 1500.00 | SALES | 30 |
| ADAMS | 1100.00 | RESEARCH | 20 |
| JAMES | 950.00 | SALES | 30 |
| FORD | 3000.00 | RESEARCH | 20 |
| MILLER | 1300.00 | ACCOUNTING | 10 |
-------------------------------------
14 rows in set (0.00 sec)--显示部门号为10的部门名员工名和工资
mysql select emp.ename,emp.sal,dept.dname,dept.deptno from emp, dept where emp.deptno dept.deptno and dept.deptno 10;
-------------------------------------
| ename | sal | dname | deptno |
-------------------------------------
| CLARK | 2450.00 | ACCOUNTING | 10 |
| KING | 5000.00 | ACCOUNTING | 10 |
| MILLER | 1300.00 | ACCOUNTING | 10 |
-------------------------------------
3 rows in set (0.00 sec)--显示各个员工的姓名工资及工资级别
mysql select ename, sal, grade from emp, salgrade where emp.sal between losal and hisal;
------------------------
| ename | sal | grade |
------------------------
| SMITH | 800.00 | 1 |
| ALLEN | 1600.00 | 3 |
| WARD | 1250.00 | 2 |
| JONES | 2975.00 | 4 |
| MARTIN | 1250.00 | 2 |
| BLAKE | 2850.00 | 4 |
| CLARK | 2450.00 | 4 |
| SCOTT | 3000.00 | 4 |
| KING | 5000.00 | 5 |
| TURNER | 1500.00 | 3 |
| ADAMS | 1100.00 | 1 |
| JAMES | 950.00 | 1 |
| FORD | 3000.00 | 4 |
| MILLER | 1300.00 | 2 |
------------------------
14 rows in set (0.00 sec)
三自连接
自连接是指在同一张表连接查询
--自连接
mysql select * from emp e1, emp e2 where e1.mgr e2.empno;
-----------------------------------------------------------------------------------------------------------------------------------------------------------
| empno | ename | job | mgr | hiredate | sal | comm | deptno | empno | ename | job | mgr | hiredate | sal | comm | deptno |
-----------------------------------------------------------------------------------------------------------------------------------------------------------
| 007788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000.00 | NULL | 20 | 007566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 |
| 007902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL | 20 | 007566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 |
| 007499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600.00 | 300.00 | 30 | 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 |
| 007521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250.00 | 500.00 | 30 | 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 |
| 007654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250.00 | 1400.00 | 30 | 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 |
| 007844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500.00 | 0.00 | 30 | 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 |
| 007900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950.00 | NULL | 30 | 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 |
| 007934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300.00 | NULL | 10 | 007782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450.00 | NULL | 10 |
| 007876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100.00 | NULL | 20 | 007788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000.00 | NULL | 20 |
| 007566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 | 007839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL | 10 |
| 007698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 | 007839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL | 10 |
| 007782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450.00 | NULL | 10 | 007839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL | 10 |
| 007369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800.00 | NULL | 20 | 007902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL | 20 |
-----------------------------------------------------------------------------------------------------------------------------------------------------------
13 rows in set (0.00 sec)--显示员工FORD的上级领导的编号和姓名mgr是员工领导的编号--empno
mysql select e1.ename,e1.mgr,e2.empno,e2.ename from emp e1, emp e2 where e1.mgr e2.empno and e1.enamee FORD;
----------------------------
| ename | mgr | empno | ename |
----------------------------
| FORD | 7566 | 007566 | JONES |
----------------------------
1 row in set (0.00 sec)
四子查询
子查询是指嵌入在其他sql语句中的select语句也叫嵌套查询
1单行查询
显示SMITH同一部门的员工
mysql select * from emp where deptno (select deptno from emp where ename smith);
--------------------------------------------------------------------------
| empno | ename | job | mgr | hiredate | sal | comm | deptno |
--------------------------------------------------------------------------
| 007369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800.00 | NULL | 20 |
| 007566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 |
| 007788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000.00 | NULL | 20 |
| 007876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100.00 | NULL | 20 |
| 007902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL | 20 |
--------------------------------------------------------------------------
5 rows in set (0.00 sec)
2多行查询
in关键字查询和10号部门的工作岗位相同的雇员的名字岗位工资部门号但是不包含10自己的
mysql select ename,job,sal,deptno from emp where job in(select distinct job from emp where deptno10)and deptno ! 10;
---------------------------------
| ename | job | sal | deptno |
---------------------------------
| JONES | MANAGER | 2975.00 | 20 |
| BLAKE | MANAGER | 2850.00 | 30 |
| SMITH | CLERK | 800.00 | 20 |
| ADAMS | CLERK | 1100.00 | 20 |
| JAMES | CLERK | 950.00 | 30 |
---------------------------------
5 rows in set (0.00 sec)
all关键字显示工资比部门30的所有员工的工资高的员工的姓名、工资和部门号
mysql select max(sal) from emp where deptno30;
----------
| max(sal) |
----------
| 2850.00 |
----------
1 row in set (0.00 sec)mysql select ename,sal,deptno from emp where sal (select max(sal) from emp where deptno30);
------------------------
| ename | sal | deptno |
------------------------
| JONES | 2975.00 | 20 |
| SCOTT | 3000.00 | 20 |
| KING | 5000.00 | 10 |
| FORD | 3000.00 | 20 |
------------------------
4 rows in set (0.01 sec)
any关键字显示工资比部门30的任意员工的工资高的员工的姓名、工资和部门号不包含自己部门的员工
mysql select ename,sal,deptno from emp where sal any(select distinct sal from emp where deptno30) and deptno30;
-------------------------
| ename | sal | deptno |
-------------------------
| JONES | 2975.00 | 20 |
| CLARK | 2450.00 | 10 |
| SCOTT | 3000.00 | 20 |
| KING | 5000.00 | 10 |
| ADAMS | 1100.00 | 20 |
| FORD | 3000.00 | 20 |
| MILLER | 1300.00 | 10 |
-------------------------
7 rows in set (0.00 sec)
3多列查询
查询和SMITH的部门和岗位完全相同的所有雇员不含SMITH本人
mysql select job,deptno from emp where enameSMITH;
---------------
| job | deptno |
---------------
| CLERK | 20 |
---------------
1 row in set (0.00 sec)mysql select * from emp where ((job,deptno) (select job,deptno from emp where enameSMITH)) and ename ! SMITH;
------------------------------------------------------------------------
| empno | ename | job | mgr | hiredate | sal | comm | deptno |
------------------------------------------------------------------------
| 007876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100.00 | NULL | 20 |
------------------------------------------------------------------------
1 row in set (0.00 sec)
4在from子句中使用子查询
子查询语句出现在from子句中。这里要用到数据查询的技巧把一个子查询当做一个临时表使用
--显示每个高于自己部门平均工资的员工的姓名、部门、工资、平均工资
mysql select ename,sal,tmp.deptno,tmp.myavg from emp,(select deptno,avg(sal) myavg from emp group by deptno)tmp where emp.deptnotmp.deptno and emp.saltmp.myavg;
-------------------------------------
| ename | sal | deptno | myavg |
-------------------------------------
| ALLEN | 1600.00 | 30 | 1566.666667 |
| JONES | 2975.00 | 20 | 2175.000000 |
| BLAKE | 2850.00 | 30 | 1566.666667 |
| SCOTT | 3000.00 | 20 | 2175.000000 |
| KING | 5000.00 | 10 | 2916.666667 |
| FORD | 3000.00 | 20 | 2175.000000 |
-------------------------------------
6 rows in set (0.00 sec)--查找每个部门工资最高的人的姓名、工资、部门、最高工资
mysql select ename,sal,emp.deptno,tmp.maxsal from emp,(select deptno,max(sal) maxsal from emp group by deptno)tmp where emp.deptnotmp.deptno and emp.saltmp.maxsal;
---------------------------------
| ename | sal | deptno | maxsal |
---------------------------------
| BLAKE | 2850.00 | 30 | 2850.00 |
| SCOTT | 3000.00 | 20 | 3000.00 |
| KING | 5000.00 | 10 | 5000.00 |
| FORD | 3000.00 | 20 | 3000.00 |
---------------------------------
4 rows in set (0.00 sec)--显示每个部门的信息部门名编号地址和人员数量
mysql select dname,dept.deptno,tmp.total from dept,(select deptno,count(*) total from emp group by depttno)tmp where tmp.deptnodept.deptno;
---------------------------
| dname | deptno | total |
---------------------------
| ACCOUNTING | 10 | 3 |
| RESEARCH | 20 | 5 |
| SALES | 30 | 6 |
---------------------------
3 rows in set (0.00 sec)mysql select dname,loc,count(*) from emp,dept where emp.deptnodept.deptno group by emp.deptno,dname,loc;
--------------------------------
| dname | loc | count(*) |
--------------------------------
| ACCOUNTING | NEW YORK | 3 |
| RESEARCH | DALLAS | 5 |
| SALES | CHICAGO | 6 |
--------------------------------
3 rows in set (0.00 sec)
5合并查询
1union
该操作符用于取得两个结果集的并集。当使用该操作符时会自动去掉结果集中的重复行。
mysql select * from emp where sal 2500 union select * from emp where jobMANAGER;
---------------------------------------------------------------------------
| empno | ename | job | mgr | hiredate | sal | comm | deptno |
---------------------------------------------------------------------------
| 7566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 |
| 7698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 |
| 7788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000.00 | NULL | 20 |
| 7839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL | 10 |
| 7902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL | 20 |
| 7782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450.00 | NULL | 10 |
---------------------------------------------------------------------------
6 rows in set (0.01 sec)
2union all
该操作符用于取得两个结果集的并集。当使用该操作符时不会去掉结果集中的重复行。
mysql select * from emp where sal 2500 union all select * from emp where jobMANAGER;
---------------------------------------------------------------------------
| empno | ename | job | mgr | hiredate | sal | comm | deptno |
---------------------------------------------------------------------------
| 7566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 |
| 7698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 |
| 7788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000.00 | NULL | 20 |
| 7839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000.00 | NULL | 10 |
| 7902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000.00 | NULL | 20 |
| 7566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975.00 | NULL | 20 |
| 7698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850.00 | NULL | 30 |
| 7782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450.00 | NULL | 10 |
---------------------------------------------------------------------------
8 rows in set (0.00 sec)
