1. Query all the information of all employees
select * from emp;
2. Check the job number, name and job of all employees
select empno, ename, job from emp;
3. select empno number, ename name, job job from emp;
4. select job from emp;
5. select distinct job from emp;
6. select distinct empno, job from emp;
Explanation: Because the employee number is not repeated, it is proved that all the columns are not repeated at this time, so the repeated columns cannot be eliminated.
7. Query the employee's number, name, and job, but the format is displayed: the employee with the number: 7369, the name is: smith, the job is: clear
select 'The employee whose ID is: ' || empno || ', whose name is: ' || ename || ', whose job is: ' || job from emp;
8. Find the name and annual salary of each employee
select ename, sal * 12 income from emp;
9. Find the information of all employees whose salary is greater than 1500
select * from emp where sal > 1500;
10. Check the information of employees who can get bonus monthly
select * from emp where comm is not null;
11. Query employee information without bonus
select * from emp where comm is null;
12. Find out the information of employees whose basic salary is greater than 1500 and who can receive bonuses
select * from emp where sal > 1500 and comm is not null;
13. Find out the information of employees whose basic salary is greater than 1500 or who can receive bonuses
select * from emp where sal > 1500 or comm is not null;
14. Find out the information of employees whose basic salary is not more than 1500 or who cannot receive bonuses
select * from emp where not(sal > 1500 and comm is not null);
15. Query the information of all employees whose basic salary is greater than 1500, but less than 3000
select * from emp where sal > 1500 and sal < 3000;
16. Query the information of all employees whose basic salary is greater than or equal to 1500, but less than or equal to 3000
select * from emp where sal >= 1500 and sal <= 3000;
select * from emp where sal between 1500 and 3000;
17. Find out the information of all employees hired in 1981 (employees hired between January 1, 1981 and December 31, 1981)
select * from emp where hiredate between '1-1月-81' and '31-12月-81';
18. Request to find out the employee information whose name is smith
select * from emp where ename = 'SMITH';
19. Request to find out the specific information of the employees whose employees are 7369, 7499, 7521
select * from emp where empno = 7369 or empno = 7499 or empno = 7521;
select * from emp where empno in(7369, 7499, 7521);
20. Request to find out the specific information of employees who are not employees of 7369, 7499, 7521
select * from emp where empno not in(7369, 7499, 7521);
21. Ask to find out the employee information whose name is smith, allen, king
select * from emp where ename in('SMITH', 'ALLEN', 'KING');
22. Find out the information of all employees whose second letter contains "M" in their names
select * from emp where ename like '_M%';
23. Find the employee information whose name contains the letter M
select * from emp where ename like '%M%';
24. Request for information on employees hired in 1981
select * from emp where hiredate like '%81%';
25. Query employee information whose salary contains 5
select * from emp where sal like '%5%';
26. Query employee information whose employee number is not 7369
select * from emp where empno != 7369;
select * from emp where empno <> 7369;
27. Requirements are sorted by salary from low to high
select * frm emp order by sal;
select * from emp order by sal asc;
28. Requirements are sorted by salary from high to low
select * from emp order by sal desc;
29. It is required to query all employee information in 20 departments. The queried information is sorted by salary from high to low. If the salary is equal, it is sorted by employment date from early to late.
select * from emp where deptno = 20 order by sal desc, hiredate asc;
30. 将小写字母变为大写字母
select upper('hello') from dual;
31. 将大写字母变为小写字母
select lower('HELLO WORLD') from dual;
32. 要求查询出姓名是 smith 的雇员信息
select * from emp where ename = upper('smith');
33. 使用 initcap() 函数将单词的第一个字母大写
select initcap('hello world') from dual;
34. 将雇员表中的雇员姓名变为开头字母大写
select initcap(ename) from emp;
35. 将字符串 "hello" 和 "world" 进行串联
select concat('hello ', 'world') from dual;
36. 对字符串进行操作的常用字符处理函数
select substr('hello', 1, 3) 截取字符串, length('hello') 字符串的长度, replace('hello', 'l', 'x') 字符串替换 from dual;
select substr('hello', 0, 3) 截取字符串, length('hello') 字符串的长度, replace('hello', 'l', 'x') 字符串替换 from dual;
37. 显示所有雇员的姓名及姓名的后三个字符
select ename, substr(ename, length(ename) -2) from emp;
select ename, substr(ename, -3, 3) from emp;
38. 使用数值函数执行四舍五入操作
select round(789.536) from dual;
39. 要求将 789.536 数值保留两位小数
select round(789.536, 2) from dual;
40. 要求将 789.536 数值中的整数的十位进行四舍五入进位
select round(789.536, -2) from dual;
41. 采用 trunc() 函数不会保留任何小数,而且小数点也不会执行四舍五入的操作
select trunc(789.536) from dual;
42. 通过 trunc() 也可以指定小数点的保留位数
select trunc(789.536, 2) from dual;
43. 作用负数表示位数
select trunc(789.536, -2) from dual;
44. 使用 mod() 函数可以进行取余的操作
select mod(10, 3) from dual;
45. 显示 10 部门雇员进入公司的星期数(当前日期 - 雇佣日期 = 天数 / 7 = 星期数)
select empno, ename, round((sysdate - hiredate) / 7) from emp where deptno = 10;
46. 日期函数
months_between(): 求出给定日期范围的月数
add_months(): 在指定的日期上加上指定的月数, 求出之后的日期
next_day(): 指定日期的下一个日期
last_day(): 求出给定日期当月的最后一天日期
47.
select empno, ename, months_between(sysdate, hiredate) from emp;
select empno, ename, round(months_between(sysdate, hiredate)) from emp;
48. select sysdate, add_months(sysdate, 4) from dual;
49. select next_day(sysdate, '星期一') from dual;
50. select last_day(sysdate) from dual;
51. 转换函数
to_char(): 转换成字符串
to_number(): 转换成数字
to_date(): 转换成日期
52. 查询所有雇员的雇员编号, 姓名, 雇佣日期
select empno,
ename,
to_char(hiredate, 'yyyy') year,
to_char(hiredate, 'mm') months,
to_char(hiredate, 'dd') day
from emp;
select empno, ename, to_char(hiredate, 'yyyy-mm-dd') from emp;
select empno, ename, to_char(hiredate, 'fmyyyy-mm-dd') from emp;
53. 查询所有雇员的编号, 姓名和工资
select empno, ename, sal from emp;
select empno, ename, to_char(sal, '99,999') from emp;
select empno, ename, to_char(sal, 'L99,999') from emp;
select empno, ename, to_char(sal, '$99,999') from emp;
54. select to_number('123') + to_number('123') from dual;
55. 将一个字符串转换成日期类型
select to_date('2009-01-01', 'yyyy-mm-dd') from dual;
56. 求出每个雇员的年薪(要求加上奖金)
select empno, ename, sal, comm, (sal + comm) * 12 from emp;
select empno, ename, sal, comm, nvl(comm, 0), (sal + nvl(comm, 0)) * 12 income from emp;
57. decode() 函数类似于 if....elsif...else 语句
select decode(1, 1, '内容是 1', 2, '内容是 2', 3, '内容是 3') from dual;
58. 查询出雇员的编号, 姓名, 雇佣日期及工作, 要求将雇员的工作替换成以下信息:
select empno 雇员编号,
ename 雇员姓名,
hiredate 雇佣日期,
decode(job,
'CLERK', '业务员',
'SALESMAN', '销售人员',
'MANAGER', '经理',
'ANALYST', '分析员',
'PRESIDENT', '总裁'
) 职位
from emp;
59. 笛卡尔积(交差连接)
select * from emp, dept;
select * from emp cross join dept;
60. 内连接
select * from emp e, dept d where e.deptno = d.deptno;
select * from emp e inner join dept d on e.deptno = d.deptno;
select * from emp e join dept d on e.deptno = d.deptno;
61. 自然连接
select * from emp natural join dept;
select * from emp e join dept d using(deptno);
62. 要求查询出雇员的编号, 姓名, 部门的编号, 名称, 地址
select e.empno, e.ename, d.deptno, d.dname, d.loc from emp e, dept d where e.deptno = d.deptno;
63. 要求查询出雇员的姓名, 工作, 雇员的直接上级领导姓名
select e.ename, e.job, m.ename from emp e, emp m where e.mgr = m.empno;
64. 要求查询出雇员的姓名, 工作, 雇员的直接上级领导姓名以及部门名称
select e.ename, e.job, m.ename, d.dname from emp e, emp m, dept d where e.mgr = m.empno and e.deptno = d.deptno;
65. 要求查询出每个雇员的姓名, 工资, 部门名称, 工资在公司的等级(salgrade), 及其领导的姓名及工资所在公司的等级
select e.ename, e.sal, d.dname, s.grade, m.ename, m.sal, ms.grade
from emp e, dept d, salgrade s, emp m, salgrade ms
where e.deptno = d.deptno
and e.sal between s.losal and s.hisal
and e.mgr = m.empno
and m.sal between ms.losal and ms.hisal;
select e.ename,
e.sal,
d.dname,
decode(s.grade, 1, '第五等级', 2, '第四等级', 3, '第三等级', 4, '第二等级', 5, '第一等级'),
m.ename,
m.sal,
decode(ms.grade, 1, '第五等级', 2, '第四等级', 3, '第三等级', 4, '第二等级', 5, '第一等级')
from emp e, dept d, salgrade s, emp m, salgrade ms
where e.deptno = d.deptno and e.sal between s.losal and s.hisal and e.mgr = m.empno
and m.sal between ms.losal and ms.hisal;
66. select empno, ename, d.deptno, dname, loc from emp e, dept d where e.deptno = d.deptno;
select empno, ename, d.deptno, dname, loc from emp e inner join dept d on e.deptno = d.deptno;
67. 左外连接
select empno, ename, d.deptno, dname, loc from emp e, dept d where e.deptno = d.deptno(+);
select empno, ename, d.deptno, dname, loc from emp e left outer join dept d on e.deptno = d.deptno;
select empno, ename, d.deptno, dname, loc from emp e left join dept d on e.deptno = d.deptno(+);
68. 右外连接
select empno, ename, d.deptno, dname, loc from emp e, dept d where e.deptno(+) = d.deptno;
select empno, ename, d.deptno, dname, loc from emp e right outer join dept d on e.deptno = d.deptno;
select empno, ename, d.deptno, dname, loc from emp e right join dept d on e.deptno = d.deptno;
69. select e.empno, e.ename, m.empno, m.ename from emp e, emp m where e.mgr = m.empno;
70. select e.empno, e.ename, m.empno, m.ename from emp e, emp m where e.mgr = m.empno(+);
71.
select * from emp e, dept d where e.deptno = d.deptno and d.deptno = 30;
select * from emp e inner join dept d on e.deptno = d.deptno where d.deptno = 30;
select * from emp e join dept d on e.deptno = d.deptno where d.deptno = 30;
select * from emp e natural join dept d where deptno = 30;
select * from emp e join dept d using(deptno) where deptno = 30;
72.
select e.ename, d.deptno, d.dname, d.loc from emp e right outer join dept d on e.deptno = d.deptno;
select e.ename, d.deptno, d.dname, d.loc from emp e right join dept d on e.deptno = d.deptno;
select e.ename, d.deptno, d.dname, d.loc from emp e, dept d where e.deptno(+) = d.deptno;
73. select count(ename) from emp;
74. select min(sal) from emp;
75. select max(sal) from emp;
76. select sum(sal) from emp;
77. select avg(sal) from emp;
78. select sum(sal) from emp where deptno = 20;
79. select avg(sal) from emp where deptno = 20;
80. 求出每个部门的雇员数量
select deptno, count(deptno) from emp group by deptno;
select deptno, count(empno) from emp group by deptno;
81. 求出每个部门的平均工资
select deptno, avg(sal) from emp group by deptno;
82. 按部门分组, 并显示部门的名称, 及每个部门的员工数
select d.dname, count(e.empno) from emp e, dept d
where e.deptno = d.deptno
group by d.dname;
select d.deptno, d.dname, temp.c
from (select deptno, count(e.empno) c from emp e group by e.deptno) temp, dept d
where temp.deptno = d.deptno;
83. 要求显示出平均工资大于 2000 的部门编号和平均工资
select deptno, avg(sal) from emp group by deptno having avg(sal) > 2000;
84. 显示非销售人员工作名称以及从事同一工作雇员的月工资的总和,并且要满足从事同一工作的雇员的月工资合计大于 5000, 输出结果按月工资的合计升序排序.
select job, sum(sal) su from emp where job <> 'SALESMAN' group by job having sum(sal) > 5000 order by su;
select temp.job, sum(temp.sal) s
from (select job, sal from emp e where job <> 'SALESMAN') temp
group by temp.job
having sum(temp.sal) > 5000
order by s;
85. 求出平均工资最高的部门工资
select max(avg(sal)) from emp group by deptno;
86. 要求查询出比雇员编号为 7654 工资高的所有雇员信息
select * from emp where sal >(select sal from emp where empno = 7654);
87. 要求查询出工资比 7654 高, 同时与 7788 从事相同工作的全部雇员信息
select * from emp
where sal >(select sal from emp where empno = 7654)
and job = (select job from emp where empno = 7788);
88. 要求查询出工资最低的雇员姓名, 工作, 工资
select ename, job, sal from emp where sal = (select min(sal) from emp);
89. 要求查询出: 部门名称，部门的员工数，部门的平均工资，部门的最低收入雇员的姓名
select d.dname, temp.c, temp.a, e.ename
from dept d,
(select deptno, count(empno) c, avg(sal) a, min(sal) m from emp group by deptno) temp,
emp e
where d.deptno = temp.deptno and e.sal = temp.m;
select d.deptno, temp.dname, temp.c, temp.a, e.ename, e.sal
from
(select d.dname , count(e.empno) c, avg(e.sal) a, min(e.sal) m
from emp e, dept d
where e.deptno = d.deptno
group by d.dname) temp,
emp e,
dept d
where temp.m = e.sal
and temp.dname = d.dname;
90. 求出每个部门的最低工资的雇员的信息
select * from emp where sal in(select min(sal) from emp group by deptno);
select * from emp where sal =any(select min(sal) from emp group by deptno);
select * from
(select min(sal) m from emp group by deptno) temp,
emp e
where e.sal = temp.m;
91. 范例 90 中, 比子查询条件中最低(小)的工资要大的雇员信息
select * from emp where sal >any(select min(sal) from emp group by deptno);
select * from emp where sal > (select min(min(sal)) from emp group by deptno);
92. 范例 90 中, 比子查询条件中最高(大)的工资要小的雇员信息
select * from emp where sal <any(select min(sal) from emp group by deptno);
select * from emp where sal < (select max(min(sal)) from emp group by deptno);
93. 范例 90 中, 比子查询条件中最高(大)的工资要大的雇员信息
select * from emp where sal >all(select min(sal) from emp group by deptno);
select * from emp where sal > (select max(min(sal)) from emp group by deptno);
94. 范例 90 中, 比子查询条件中最低(小)的工资要小的雇员信息
select * from emp where sal <all(select min(sal) from emp group by deptno);
select * from emp where sal < (select min(min(sal)) from emp group by deptno);
95. 查找出 20 部门中没有奖金的雇员信息
select * from emp where (sal, nvl(comm, -1)) in (select sal, nvl(comm, -1) from emp where deptno = 20);
select * from emp where deptno = 20 and comm is null;
96. union 操作符返回两个查询选定的所有不重复的行
select deptno from emp union select deptno from dept;
97. union all 操作符合并两个查询选定的所有行，包括重复的行
select deptno from emp union all select deptno from dept;
98. intersect 操作符只返回两个查询都有的行
select deptno from emp intersect select deptno from dept;
99. minus 操作符只返回由第一个查询选定但是没有被第二个查询选定的行, 也就是在第一个查询结果中排除在第二个查询结果中出现的行
select deptno from dept minus select deptno from emp;