常用sql语句

使用scott/tiger用户下的emp表完成下列练习，表的结构说明如下
emp员工表 字段内容如下:
empno  员工号
ename  员工姓名
job      工作
mgr      上级编号
hiredate     受雇日期
sal      薪金
comm  佣金
deptno  部门编号

1.选择部门30中的所有员工.
  SELECT * FROM EMP WHERE DEPTNO = 30
2.列出所有办事员(CLERK)的姓名，编号和部门编号.
  SELECT EMPNO,ENAME,DEPTNO FROM EMP WHERE JOB = 'CLERK'
3.找出佣金高于薪金的员工.
   SELECT * FROM EMP WHERE COMM > SAL
4.找出佣金高于薪金的60%的员工.
SELECT * FROM EMP WHERE COMM > SAL * 0.6
   
5.找出部门10中所有经理(MANAGER)和部门20中所有办事员(CLERK)的详细资料.
   SELECT * FROM EMP WHERE JOB = 'MANAGER' AND DEPTNO = 10 OR JOB = 'CLERK' AND DEPTNO = 20
6.找出部门10中所有经理(MANAGER),部门20中所有办事员(CLERK),既不是经理又不是办事员但其薪金大于或等于2000的所有员工的详细资料.
SELECT * FROM EMP WHERE (JOB = 'MANAGER' AND DEPTNO = 10) OR (JOB = 'CLERK' AND DEPTNO = 20) OR (JOB != 'MANAGER' AND JOB != 'CLERK' AND SAL >= 2000)

7.找出收取佣金的员工的不同工作.
SELECT DISTINCT JOB FROM EMP WHERE COMM IS NOT NULL
8.找出不收取佣金或收取的佣金低于100的员工.
   SELECT DISTINCT JOB FROM EMP WHERE COMM IS NOT NULL
10.找出早于12年前受雇的员工.
SELECT * FROM EMP WHERE EXTRACT(YEAR FROM SYSDATE) - EXTRACT(YEAR FROM HIREDATE) > 12
11.以首字母大写的方式显示所有员工的姓名.
1．SELECT INITCAP(ENAME) FROM EMP
2．
SELECT CONCAT(UPPER(SUBSTR(ENAME,1,1)),LOWER(SUBSTR(ENAME,2,LENGTH(ENAME)))) FROM EMP
12.显示正好为5个字符的员工的姓名.
SELECT * FROM EMP WHERE LENGTH(ENAME) = 5
13.显示不带有"R"的员工的姓名.
SELECT * FROM EMP WHERE EMPNO NOT IN (SELECT EMPNO FROM EMP WHERE ENAME LIKE '%R%')
14.显示所有员工姓名的前三个字符.
   SELECT SUBSTR(ENAME,1,3) FROM EMP
15.显示所有员工的姓名,用a替换所有"A"
  SELECT REPLACE(ENAME,'A','a') FROM EMP
16.显示满10年服务年限的员工的姓名和受雇日期.
SELECT ENAME,HIREDATE FROM EMP WHERE EXTRACT(YEAR FROM SYSDATE) - EXTRACT(YEAR FROM HIREDATE) >= 10
17.显示员工的详细资料,按姓名排序.
SELECT * FROM EMP ORDER BY ENAME

18.显示员工的姓名和受雇日期,根据其服务年限,将最老的员工排在最前面.
   SELECT ENAME,HIREDATE FROM EMP   ORDER BY EXTRACT(YEAR FROM SYSDATE) - EXTRACT(YEAR       FROM HIREDATE) DESC
19.显示所有员工的姓名、工作和薪金,按工作的降序排序,若工作相同则按薪金排序.
  SELECT ENAME,JOB,SAL FROM EMP ORDER BY JOB DESC,SAL
20.显示所有员工的姓名、加入公司的年份和月份,按受雇日期所在月排序,若月份相同则将最早年份的员工排在最前面.
     SELECT ENAME AS 姓名,EXTRACT(YEAR FROM HIREDATE) AS 年份,EXTRACT(MONTH FROM HIREDATE) AS 月份  FROM EMP ORDER BY EXTRACT(MONTH FROM HIREDATE),EXTRACT(YEAR FROM HIREDATE)
  
21.找出在(任何年份的)2月受聘的所有员工。
     SELECT * FROM EMP WHERE EXTRACT(MONTH FROM HIREDATE) = 2
22.显示姓名字段的任何位置包含"A"的所有员工的姓名.
    SELECT * FROM EMP WHERE ENAME LIKE ‘%A%’