SQL> --查询工资比SCOTT高的员工信息
SQL> --1. SCOTT的工资
SQL> select sal from emp where ename='SCOTT';SAL
---------- 3000 SQL> --2. 比3000高的员工
SQL> set linesize 200
SQL> select * from emp where sal > 3000;EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7839 KING PRESIDENT 17-11月-81 5000 10 SQL> --子查询所要解决的问题：不能一步求解
SQL> select *2 from emp3 where sal > (select sal4 from emp5 where ename='SCOTT');EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7839 KING PRESIDENT 17-11月-81 5000 10 SQL> /*
SQL> 注意的问题：
SQL> 1. 括号
SQL> 2. 合理的书写风格
SQL> 3. 可以在主查询的where select having from后面都可以放置子查询
SQL> 4. 不可以在group by放置子查询
SQL> 5. 强调from后面的子查询
SQL> 6. 主查询和子查询可以不是同一张表；只要子查询返回的结果主查询可以使用即可
SQL> 7. 一般不在子查询排序；但在top-n分析问题中，必须对子查询排序
SQL> 8. 一般先执行子查询，再执行主查询；但相关子查询例外
SQL> 9. 单行子查询只能使用单行操作符；多行子查询只能使用多行操作符
SQL> 10. 子查询中的null,若子查询的结果中含有null值，则不能使用not in来判断，可以使用in判断
SQL> */
SQL> --3. 可以在主查询的where select having from后面都可以放置子查询
SQL> select empno,ename,sal,(select job from emp where empno=7839) 第四列2 from emp;EMPNO ENAME SAL 第四列
---------- ---------- ---------- --------- 7369 SMITH 800 PRESIDENT 7499 ALLEN 1600 PRESIDENT 7521 WARD 1250 PRESIDENT 7566 JONES 2975 PRESIDENT 7654 MARTIN 1250 PRESIDENT 7698 BLAKE 2850 PRESIDENT 7782 CLARK 2450 PRESIDENT 7788 SCOTT 3000 PRESIDENT 7839 KING 5000 PRESIDENT 7844 TURNER 1500 PRESIDENT 7876 ADAMS 1100 PRESIDENT EMPNO ENAME SAL 第四列
---------- ---------- ---------- --------- 7900 JAMES 950 PRESIDENT 7902 FORD 3000 PRESIDENT 7934 MILLER 1300 PRESIDENT 已选择 14 行。SQL> --5. 强调from后面的子查询
SQL> --查询员工信息：员工号 姓名 月薪
SQL> select *2 from (select empno,ename,sal from emp);EMPNO ENAME SAL
---------- ---------- ---------- 7369 SMITH 800 7499 ALLEN 1600 7521 WARD 1250 7566 JONES 2975 7654 MARTIN 1250 7698 BLAKE 2850 7782 CLARK 2450 7788 SCOTT 3000 7839 KING 5000 7844 TURNER 1500 7876 ADAMS 1100 EMPNO ENAME SAL
---------- ---------- ---------- 7900 JAMES 950 7902 FORD 3000 7934 MILLER 1300 已选择 14 行。SQL> --查询员工信息：员工号 姓名 月薪 年薪
SQL> ed
已写入 file afiedt.buf1 select *2* from (select empno,ename,sal,sal*12 annsal from emp)
SQL> /EMPNO ENAME SAL ANNSAL
---------- ---------- ---------- ---------- 7369 SMITH 800 9600 7499 ALLEN 1600 19200 7521 WARD 1250 15000 7566 JONES 2975 35700 7654 MARTIN 1250 15000 7698 BLAKE 2850 34200 7782 CLARK 2450 29400 7788 SCOTT 3000 36000 7839 KING 5000 60000 7844 TURNER 1500 18000 7876 ADAMS 1100 13200 EMPNO ENAME SAL ANNSAL
---------- ---------- ---------- ---------- 7900 JAMES 950 11400 7902 FORD 3000 36000 7934 MILLER 1300 15600 已选择 14 行。SQL> --6. 主查询和子查询可以不是同一张表；只要子查询返回的结果主查询可以使用即可
SQL> --查询部门名称是SALES的员工信息
SQL> select *2 from emp3 where deptno=(select deptno4 from dept5 where dname='SALES');EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7900 JAMES CLERK 7698 03-12月-81 950 30 已选择 6 行。SQL> select e.*2 from emp e,dept d3 where e.deptno=d.deptno and d.dname='SALES';EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7900 JAMES CLERK 7698 03-12月-81 950 30 已选择 6 行。SQL> --SQL优化 4： 理论上，尽量使用多表查询
SQL> host clsSQL> --in 在集合中
SQL> --查询部门名称是SALES和ACCOUNTING的员工
SQL> select *2 from emp3 where deptno in (select deptno frmo dept where dname='SALES' or dname='ACCOUNTING');
where deptno in (select deptno frmo dept where dname='SALES' or dname='ACCOUNTING')*
第 3 行出现错误:
ORA-00923: 未找到要求的 FROM 关键字 SQL> ed
已写入 file afiedt.buf1 select *2 from emp3* where deptno in (select deptno from dept where dname='SALES' or dname='ACCOUNTING')
SQL> /EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7782 CLARK MANAGER 7839 09-6月 -81 2450 10 7839 KING PRESIDENT 17-11月-81 5000 10 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7900 JAMES CLERK 7698 03-12月-81 950 30 7934 MILLER CLERK 7782 23-1月 -82 1300 10 已选择 9 行。SQL> select e.*2 from emp e,dept d3 where e.deptno=d.deptno and (d.dname='SALES' or d.dname='ACCOUNTING');EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7782 CLARK MANAGER 7839 09-6月 -81 2450 10 7839 KING PRESIDENT 17-11月-81 5000 10 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7900 JAMES CLERK 7698 03-12月-81 950 30 7934 MILLER CLERK 7782 23-1月 -82 1300 10 已选择 9 行。SQL> host clsSQL> --any: 和集合中任意一个值比较
SQL> --查询工资比30号部门任意一个员工高的员工信息
SQL> select *2 from emp3 where sal > any (select sal from emp where deptno=30);EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7839 KING PRESIDENT 17-11月-81 5000 10 7902 FORD ANALYST 7566 03-12月-81 3000 20 7788 SCOTT ANALYST 7566 19-4月 -87 3000 20 7566 JONES MANAGER 7839 02-4月 -81 2975 20 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7782 CLARK MANAGER 7839 09-6月 -81 2450 10 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7934 MILLER CLERK 7782 23-1月 -82 1300 10 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7876 ADAMS CLERK 7788 23-5月 -87 1100 20 已选择 12 行。SQL> ed
已写入 file afiedt.buf1 select *2 from emp3* where sal > (select min(sal) from emp where deptno=30)
SQL> /EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7566 JONES MANAGER 7839 02-4月 -81 2975 20 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7782 CLARK MANAGER 7839 09-6月 -81 2450 10 7788 SCOTT ANALYST 7566 19-4月 -87 3000 20 7839 KING PRESIDENT 17-11月-81 5000 10 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7876 ADAMS CLERK 7788 23-5月 -87 1100 20 7902 FORD ANALYST 7566 03-12月-81 3000 20 EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7934 MILLER CLERK 7782 23-1月 -82 1300 10 已选择 12 行。SQL> --all: 和集合中的所有值比较
SQL> --查询工资比30号部门所有员工高的员工信息
SQL> select *2 from emp3 where sal > all (select sal from emp where deptno=30);EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7566 JONES MANAGER 7839 02-4月 -81 2975 20 7788 SCOTT ANALYST 7566 19-4月 -87 3000 20 7839 KING PRESIDENT 17-11月-81 5000 10 7902 FORD ANALYST 7566 03-12月-81 3000 20 SQL> ed
已写入 file afiedt.buf1 select *2 from emp3* where sal > (select max(sal) from emp where deptno=30)
SQL> /EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7566 JONES MANAGER 7839 02-4月 -81 2975 20 7788 SCOTT ANALYST 7566 19-4月 -87 3000 20 7839 KING PRESIDENT 17-11月-81 5000 10 7902 FORD ANALYST 7566 03-12月-81 3000 20 SQL> host clsSQL> --多行子查询中的null
SQL> --not in (10,20,null)
SQL> --查询不是老板的员工
SQL> select * from emp;EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7369 SMITH CLERK 7902 17-12月-80 800 20 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7566 JONES MANAGER 7839 02-4月 -81 2975 20 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7782 CLARK MANAGER 7839 09-6月 -81 2450 10 7788 SCOTT ANALYST 7566 19-4月 -87 3000 20 7839 KING PRESIDENT 17-11月-81 5000 10 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7876 ADAMS CLERK 7788 23-5月 -87 1100 20 EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7900 JAMES CLERK 7698 03-12月-81 950 30 7902 FORD ANALYST 7566 03-12月-81 3000 20 7934 MILLER CLERK 7782 23-1月 -82 1300 10 已选择 14 行。SQL> select *2 from emp3 where empno not in (select mgr from emp);未选定行SQL> --查询是老板的员工
SQL> ed
已写入 file afiedt.buf1 select *2 from emp3* where empno in (select mgr from emp)
SQL> /EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7902 FORD ANALYST 7566 03-12月-81 3000 20 7698 BLAKE MANAGER 7839 01-5月 -81 2850 30 7839 KING PRESIDENT 17-11月-81 5000 10 7566 JONES MANAGER 7839 02-4月 -81 2975 20 7788 SCOTT ANALYST 7566 19-4月 -87 3000 20 7782 CLARK MANAGER 7839 09-6月 -81 2450 10 已选择 6 行。SQL> select *2 from emp3 where empno not in (select mgr from emp where mgr is not null);EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 7521 WARD SALESMAN 7698 22-2月 -81 1250 500 30 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 7934 MILLER CLERK 7782 23-1月 -82 1300 10 7369 SMITH CLERK 7902 17-12月-80 800 20 7876 ADAMS CLERK 7788 23-5月 -87 1100 20 7900 JAMES CLERK 7698 03-12月-81 950 30 已选择 8 行。SQL> spool off
SQL> --rownum 伪列 行号
SQL> select rownum,empno,ename,sal from emp;ROWNUM EMPNO ENAME SAL
---------- ---------- ---------- ---------- 1 7369 SMITH 800 2 7499 ALLEN 1600 3 7521 WARD 1250 4 7566 JONES 2975 5 7654 MARTIN 1250 6 7698 BLAKE 2850 7 7782 CLARK 2450 8 7788 SCOTT 3000 9 7839 KING 5000 10 7844 TURNER 1500 11 7876 ADAMS 1100 ROWNUM EMPNO ENAME SAL
---------- ---------- ---------- ---------- 12 7900 JAMES 950 13 7902 FORD 3000 14 7934 MILLER 1300 已选择 14 行。SQL> select rownum,empno,ename,sal2 from emp3 where rownum<=34 order by sal desc;ROWNUM EMPNO ENAME SAL
---------- ---------- ---------- ---------- 2 7499 ALLEN 1600 3 7521 WARD 1250 1 7369 SMITH 800 SQL> /*
SQL> 关于rownum
SQL> 1. rownum永远按照默认的顺序生成
SQL> 2. rownum只能使用< <=;不能使用> >=
SQL> */
SQL> select rownum,empno,ename,sal from emp order by sal desc;ROWNUM EMPNO ENAME SAL
---------- ---------- ---------- ---------- 9 7839 KING 5000 13 7902 FORD 3000 8 7788 SCOTT 3000 4 7566 JONES 2975 6 7698 BLAKE 2850 7 7782 CLARK 2450 2 7499 ALLEN 1600 10 7844 TURNER 1500 14 7934 MILLER 1300 3 7521 WARD 1250 5 7654 MARTIN 1250 ROWNUM EMPNO ENAME SAL
---------- ---------- ---------- ---------- 11 7876 ADAMS 1100 12 7900 JAMES 950 1 7369 SMITH 800 已选择 14 行。SQL> select rownum,empno,ename,sal2 from (select * from emp order by sal desc)3 where rownum<=3;ROWNUM EMPNO ENAME SAL
---------- ---------- ---------- ---------- 1 7839 KING 5000 2 7788 SCOTT 3000 3 7902 FORD 3000 SQL> -- 2. rownum只能使用< <=;不能使用> >=
SQL> select rownum,empno,ename,sal from emp where rownum>=5 and rownum<=8;未选定行SQL> select rownum,empno,ename,sal from emp where rownum>=5;未选定行SQL> select rownum,empno,ename,sal from emp where rownum<=8;ROWNUM EMPNO ENAME SAL
---------- ---------- ---------- ---------- 1 7369 SMITH 800 2 7499 ALLEN 1600 3 7521 WARD 1250 4 7566 JONES 2975 5 7654 MARTIN 1250 6 7698 BLAKE 2850 7 7782 CLARK 2450 8 7788 SCOTT 3000 已选择 8 行。SQL> select *2 from (select rownum r,e1.*3 from (select * from emp order by sal) e14 where rownum <=85 )6 where r >=5;R EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- ---------- --------- ---------- -------------- ---------- ---------- ---------- 5 7654 MARTIN SALESMAN 7698 28-9月 -81 1250 1400 30 6 7934 MILLER CLERK 7782 23-1月 -82 1300 10 7 7844 TURNER SALESMAN 7698 08-9月 -81 1500 0 30 8 7499 ALLEN SALESMAN 7698 20-2月 -81 1600 300 30 SQL> --临时表
SQL> --create global temporary table ******
SQL> --特点：当事务或者会话结束的时候，表中的数据自动删除
SQL> create global temporary table test12 (tid number,3 tname varchar2(20))4 on commit delete rows;表已创建。SQL> insert into test1 values(1,'Tom');已创建 1 行。SQL> select * from test1;TID TNAME
---------- -------------------- 1 Tom SQL> commit;提交完成。SQL> select * from test1;未选定行SQL>
SQL> create global temporary table test22 (tid number,3 tname varchar2(20))4 on commit reserve rows;
on commit reserve rows*
第 4 行出现错误:
ORA-00901: 无效 CREATE 命令 SQL> create global temporary table test22 (tid number,3 tname varchar2(20))4 on commit preserve rows;表已创建。SQL> insert into test2 values(1,'Tom');已创建 1 行。SQL> commit;提交完成。SQL> select * from test2;TID TNAME
---------- -------------------- 1 Tom SQL> exit
SQL> host clsSQL> --第二题
SQL> select e.empno,e.ename,e.sal,d.avgsal2 from emp e, (select deptno,avg(sal) avgsal from emp group by deptno) d3 where e.deptno=d.deptno and e.sal> d.avgsal;EMPNO ENAME SAL AVGSAL
---------- ---------- ---------- ---------- 7698 BLAKE 2850 1566.66667 7499 ALLEN 1600 1566.66667 7902 FORD 3000 2175 7788 SCOTT 3000 2175 7566 JONES 2975 2175 7839 KING 5000 2916.66667 已选择 6 行。SQL> --相关子查询：将主查询的值作为参数传递给子查询
SQL> select empno,ename,sal,(select avg(sal) from emp where deptno=e.deptno) avgsal2 from emp e3 where sal > (select avg(sal) from emp where deptno=e.deptno);EMPNO ENAME SAL AVGSAL
---------- ---------- ---------- ---------- 7499 ALLEN 1600 1566.66667 7566 JONES 2975 2175 7698 BLAKE 2850 1566.66667 7788 SCOTT 3000 2175 7839 KING 5000 2916.66667 7902 FORD 3000 2175 已选择 6 行。SQL> host clsSQL> --第三题
SQL> select hiredate from emp;HIREDATE
--------------
17-12月-80
20-2月 -81
22-2月 -81
02-4月 -81
28-9月 -81
01-5月 -81
09-6月 -81
19-4月 -87
17-11月-81
08-9月 -81
23-5月 -87 HIREDATE
--------------
03-12月-81
03-12月-81
23-1月 -82 已选择 14 行。SQL> /*
SQL> select count(*) Total,
SQL>
SQL> sum(if 是81年 then +1 else +0) "1981",
SQL> from emp;
SQL>
SQL> HIREDATE count81:=0
SQL> --------------------------
SQL> 17-12月-80 0
SQL> 20-2月 -81 1
SQL> 22-2月 -81 1
SQL> 02-4月 -81 1
SQL> 28-9月 -81 1
SQL> 01-5月 -81 1
SQL> 09-6月 -81 1
SQL> 19-4月 -87 0
SQL> 17-11月-81 1
SQL> 08-9月 -81 1
SQL> 23-5月 -87 0
SQL> 03-12月-81 1
SQL> 03-12月-81 1
SQL> 23-1月 -82 0
SQL> -----------------------------
SQL> 10
SQL> */
SQL> host clsSQL> --行转列
SQL> -- wm_concat(字符串) 组函数
SQL> select deptno,wm_concat(ename) nameslist2 from emp3 group by deptno;DEPTNO
----------
NAMESLIST
--------------------------------------------------------------------------------10
CLARK,KING,MILLER 20
SMITH,FORD,ADAMS,SCOTT,JONES 30
ALLEN,BLAKE,MARTIN,TURNER,JAMES,WARD SQL> col NAMESLIST for a60
SQL> select deptno,wm_concat(ename) nameslist2 from emp3 group by deptno;DEPTNO NAMESLIST
---------- ------------------------------------------------------------ 10 CLARK,KING,MILLER 20 SMITH,FORD,ADAMS,SCOTT,JONES 30 ALLEN,BLAKE,MARTIN,TURNER,JAMES,WARD SQL> spool off
--oracle分页select *from (select rownum r,e1.*from (select * from emp order by sal) e1where rownum <=8)where r >=5;SQL> select count(*) Total,2 sum(decode(to_char(hiredate,'yyyy'),'1980',1,0)) "1980",3 sum(decode(to_char(hiredate,'yyyy'),'1981',1,0)) "1981",4 sum(decode(to_char(hiredate,'yyyy'),'1982',1,0)) "1982",5 sum(decode(to_char(hiredate,'yyyy'),'1987',1,0)) "1987"6 from emp;TOTAL 1980 1981 1982 1987
---------- ---------- ---------- ---------- ---------- 14 1 10 1 2