简单查询
01.查询员工表所有数据，并说明使用*的缺点
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select *from emp; |
02.查询职（job）为‘PRESIDENT‘的员工的工资
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select sal from emp where job=’PRESIDENT’; |
03.查询佣金为0或为null的员工的信息
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select *from emp where comm is null or comm=0; |
03.查询入职日期在1981-5-1到1981-12-31之间的所有员工的信息
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select *from emp where hiredate between to_date(‘1-5月-1981‘) and to_date(‘31-12月-1981‘); |
05.查询所有名字长度为4的员工的员工的编号，姓名
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select empno,ename from emp where length(ename)=4; |
06. 显示10号部门饿所有经理和20号部门的所有员工
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select *from emp where (deptno=10 and job=‘MANAGER‘) or deptno=20; |
07. 显示姓名没有‘L‘字的员工的详细信息或含有‘SM‘字的员工信息
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select *from emp where ename not like ‘%L%‘ or ename like ‘%SM%‘; |
08. 显示各个部门经理的工资
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select deptno,sal from emp where job=‘MANAGER‘; |
09．显示佣金收入比工资高的员工的详细信息
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select *from emp where COMM>SAL; |
10.把hiredate列看做是员工的生日，求本月过生日的员工：
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select *from emp where extract(month from hiredate)=extract(month from sysdate); |
11. 把hiredate列看做是员工的生日，求下月过生日的员工
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select *from emp where to_char(hiredate,‘mm‘)=to_char(add_months(sysdate,1),‘mm‘); |
12.求1982年入职的员工
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select *from emp where to_char(hiredate,‘yyyy‘)=1982; |
13. 求1981年下半年入职的员工
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select *from emp where hiredate between to_date(‘1981-7-1‘,‘yyyy-mm-dd‘) and to_date(‘1982-1-1‘,‘yyyy-mm-dd‘)-1; |
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select *from emp where extract(year from hiredate)=1981 and extract(month from hiredate)>6; |
14. 求1981年各个月入职的员工个数
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select to_char(hiredate,‘mm‘),count(*) from emp where to_char(hiredate,‘yyyy‘)=‘1981‘ group by to_char(hiredate,‘mm‘) order by to_char(hiredate,‘mm‘); |
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select extract(month from hiredate),count(*) from emp where extract(year from hiredate)=1981 group by extract(month from hiredate) order by extract(month from hiredate); |
子查询
01 .查询各个部门的平均工资
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select deptno,avg(nvl(sal,0)) from emp group by deptno; |
02.显示各种职位的最低工资
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select job,min(sal) from emp group by job; |
03．按照入职日期由新到旧排列员工信息
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select *from emp order by hiredate desc; |
04．查询员工的基本信息，附加其上级的姓名（自关联）
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select e.*,d.ename from emp e,emp d where e.mgr=d.empno; |
05．显示工资比’ALLEN’高的所有员工的姓名和工作
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select ename,job,sal from emp where sal> (select sal from emp where ename=‘ALLEN‘); |
06．显示与scott从事相同工作的员工的信息（子查询）
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select *from emp where job= (select job from emp where ename=‘SCOTT‘); |
07．显示销售部(‘SALES’)员工的姓名
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select e.ename from emp e inner join dept d on e.deptno=d.deptno where d.dname=‘SALES‘; |
08．显示与30号门’MARTIN’员工工资相同的员工的姓名和工资
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select ename,sal from emp where sal= (select sal from emp where ename=‘MARTIN‘ and deptno=30); |
09．查询所有工资高于平均工资（包括所有员工）的销售人员
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select *from emp where sal> (select avg(nvl(sal,0)) from emp) and job=‘SALESMAN‘; |
10．显示所有职员的姓名及其所在部门的名称和工资(表连接)
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select e.ename,e.sal,d.dname from emp e inner join dept d on e.deptno=d.deptno; |
11．查询在研发部(RESEARCH)工作人员的编号，姓名，工作部门，工作所在地
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select e.empno,e.ename,e.deptno,d.loc from emp e inner join dept d on e.deptno=d.deptno where d.dname=‘RESEARCH‘; |
12．查询各个部门的名称和员工人数
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select d.dname,e.deptno,count(*) from emp e inner join dept d on e.deptno=d.deptno group by e.deptno,d.dname; |
13．查询各个部门员工工资大于平均工资（平均工资包括所有员工）的人数和员工职位(子查询)
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select count(*),job from emp where sal> (select avg(nvl(sal,0)) from emp) group by job; |
14．查询工资相同的员工的工资和姓名（子查询）
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select sal,ename from emp e where exists (select 1 from emp where e.sal=sal and e.ename<>ename); 或 select sal,ename from emp e where(select count(*) from emp where sal=e.sal group by sal)>1; 或 select e.sal,e.ename from emp e,emp d where e.sal=d.sal and e.ename<>d.ename; |
15．查询工资最高的3名员工信息(排序)
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select rownum,e.* from (select *from emp order by sal desc) e where rownum<=3; |
16．按工资进行排名：排名从1开始，工资相同排名相同（如果两个并列第1则没有地2名，从第三名继续排）
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select ename,rank() over(order by sal desc) from emp; |
17．求入职日期相同的（年月日相同）的员工
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select *from emp e where exists (select 1 from emp where e.hiredate=hiredate and e.ename<>ename); |
18．查询每个部门的最高工资
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select deptno,max(sal) from emp group by deptno; |
19．查询每个部门，每个职位的最高工资
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select deptno,job,max(sal) from emp group by deptno,job order by deptno asc; |
20．查询每个员工的信息及工资级别，用到表(Salgrade)
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select e.*, decode (s.grade,1,‘第五等工资‘, 2,‘第四等工资‘, 3,‘第三等工资‘, 4,‘第二等工资‘, 5,‘第一等工资‘) new_sal from emp e,salgrade s where e.sal between s.losal and s.hisal; |
21.查询工资最高的第6-10名
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select * from (select rownum r,e.* from (select *from emp order by sal desc) e) where r>=6 and r<=10; |
22．查询各个部门工资最高的员工信息
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select *from emp e where e.sal= (select max(sal) from emp where e.deptno=deptno group by deptno ); 或 select *from emp e,(select deptno,max(sal) m from emp group by deptno) d where e.deptno=d.deptno and e.sal=d.m; |
23．查询每个部门工资最高的前2名员工
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select * from (select e.*,row_number() over(partition by deptno order by sal) r from emp e) where r<=2; 或 select *from emp e where 2> (select count(*) from emp where sal>e.sal and e.deptno=deptno) order by deptno,sal desc; |
24．查询出有3个以上下属的员工信息（自关联）
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select *from emp e where (select count(*) from emp where e.empno=mgr)>2; 或 select *from emp e where exists (select mgr,count(*) from emp where e.empno=mgr group by mgr having count(*)>2); |
25．查询所有大于本部平均工资的员工信息
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select *from emp e where sal> (select avg(nvl(sal,0)) from emp where e.deptno=deptno group by deptno) order by sal; |
26．查询平均工资最高的部门信息
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select e.deptno,e.r,d.* from (select rownum s,deptno,r from (select deptno,avg(nvl(sal,0)) r from emp group by deptno order by avg(nvl(sal,0)) desc)) e,dept d where s=1 and e.deptno=d.deptno; |
27．查询大于各个部门总工资的平均值的部门信息
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select s.deptno,s.av,d.* from (select e.deptno,avg(nvl(sal,0)) av from emp e where (select avg(nvl(sal,0)) from emp where e.deptno=deptno)> (select avg(nvl(sal,0)) from emp) group by deptno) s,dept d where s.deptno=d.deptno; 或 select e.deptno,avg(nvl(e.sal,0)),d.dname,d.loc from emp e,dept d where (select avg(nvl(sal,0)) from emp where e.deptno=deptno)> (select avg(nvl(sal,0)) from emp) and e.deptno=d.deptno group by e.deptno,d.dname,d.loc; |
28．查询大于各个部门总工资平均值的部门下的员工信息
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select e.* from emp e where sal> (select avg(nvl(sal,0)) from emp where e.deptno=deptno); |
29．查询么有员工的部门信息
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select *from dept where deptno not in (select deptno from emp group by deptno); |
复杂查询
1.列出至少有一个雇员的所有部门信息（嵌套子查询）
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select * from dept d where exists (select e.deptno from emp e where e.deptno=d.deptno); 或 select distinct * from dept d where d.deptno in (select e.deptno from emp e where e.deptno=d.deptno); |
2、列出薪金(工资)比‘SMITH‘多的所有雇员信息（嵌套子查询）
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select * from emp where sal> (select sal from emp e where e.ename=‘SMITH‘); |
3、列出所有雇员的姓名及其上级的姓名（自表外连接）
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select e.ename 员工,d.ename 老板 from emp e left join emp d on e.mgr=d.empno; 或 select e.ename 员工,d.ename 老板 from emp e,emp d where e.mgr=d.empno(+); |
4、列出入职日期(雇佣日期)早于其直接上级的所有雇员（自表连接）
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select * from emp e where e.hiredate> (select hiredate from emp where e.mgr=empno); |
5、列出部门名称和这些部门的雇员，同时列出那些没有雇员的部门（外连接）
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select d.dname,e.ename from dept d left join emp e on d.deptno=e.deptno; 或 select d.dname,e.ename from dept d,emp e where e.deptno(+)=d.deptno; |
6、列出所有‘CLERK‘(办事员)的姓名及其部门名称（内连接）
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select e.ename,d.dname from emp e join dept d on e.deptno=d.deptno and e.job=‘CLERK‘; |
7、列出各种工作的最低薪金，并使最低薪金大于1500（分组和过滤）
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select job,min(sal) from emp group by job having min(sal)>1500; |
8、列出从事sales(销售)工作的雇员的姓名，假定不知道销售部的部门编号
（使用嵌套子查询进行连接）
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select e.ename from emp e where e.deptno= (select d.deptno from dept d where d.dname=upper(‘sales‘)); |
9、列出薪金高于公司平均水平的所有雇员信息（聚合函数）
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select * from emp where sal> (select avg(nvl(sal,0)) from emp); |
10、列出与"SCOTT"从事相同工作的所有雇员（嵌套自查询）
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select * from emp where job= (select job from emp where ename=upper(‘SCOTT‘)); |
11、列出薪金等于在部门30工作的雇员的所有姓名和薪金（有问题）
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select e.ename,e.sal,e.deptno from emp e where e.sal in (select sal from emp where deptno=30); 或 select ename,sal,deptno from emp where deptno=30; |
12、列出薪金高于在部门30工作的所有雇员的姓名和薪金（嵌套子查询）
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select ename,sal from emp where sal> (select max(sal) from emp where deptno=30); 或 select ename,sal from emp where sal>all (select sal from emp where deptno=30); |
13、列出每个部门的信息（外连接）
以及该部门中（分组）雇员的数量（外连接并分组）
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select d.dname,d.loc,count(e.empno) from emp e right join dept d on e.deptno=d.deptno group by d.dname,d.loc; |
14、列出所有雇员的姓名、部门名称和薪金(外连接)
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select e.ename,d.dname,e.sal from emp e left join dept d on d.deptno=e.deptno; |
15、列出从事同一种工作但属于不同的部门的雇员的不同组合(自表笛卡尔积)
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select e.ename,d.ename from emp e,emp d where e.job=d.job and e.deptno<>d.deptno and e.ename<d.ename;--比较字母的大小,是两个字符串的字母逐一比较的 |
16、列出分配有雇员数量（聚合函数）的所有部门（按部门分组并进行外连接）的详细信息，即使分配有零个雇员
这求出的是至少有一名雇员的部门信息.
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select d.deptno,d.dname,d.loc,count(e.empno) from emp e right join dept d on e.deptno=d.deptno group by d.deptno,d.dname,d.loc; 或 select d.deptno,d.dname,d.loc,count(e.empno) from emp e,dept d where e.deptno(+)=d.deptno group by d.deptno,d.dname,d.loc; |
17、列出各种类别工作（分组）的最低工资
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select job,min(sal) from emp group by job; |
19、列出按计算字段的排序的所有雇员的年薪(计算字段指的是年薪)
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select (sal+nvl(COMM,0))*12 as avs from emp order by avs; |
20、列出薪金水平处于第四位的雇员信息（多重嵌套查询）
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select * from emp where sal= (select sal from (select rownum r,sal from (select sal from emp order by sal desc)) where r=4); 或 select * from (select e.*,dense_rank() over(order by sal desc) d from emp e) where d=4; |
21、查询各部门薪水最高的员工
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select * from emp e where sal= (select max(sal) from emp where e.deptno=deptno group by deptno); 或 select * from emp e,(select max(sal) sal from emp group by deptno) s where e.sal=s.sal; |
