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> --多表查询
SQL> select e.*
2 from dept d,emp e
3 where d.dname='SALES' and d.deptno=e.deptno;
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。
一个数据库优化问题（子查询与多表查询）
SQL> --如果子查询和多表查询均可，一般采用多表查询 （子查询要查询两次数据库，多表查询查询一次）
单行子查询
子查询结果只返回一行
使用单行比较操作符
查询示例：
SELECTlast_name,job_id<??http://www.2cto.com/kf/ware/vc/" target="_blank" class="keylink">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"SALES' or 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> ed
已写入 file afiedt.buf
1 select *
2 from emp
3* where deptno not in (select deptno from dept where dname='SALES' or dname='ACCOUNTING')
SQL> /
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------------- ----- ---------- ----------
7369 SMITH CLERK 7902 17-12月-80 800 20
7566 JONES MANAGER 7839 02-4月 -81 2975 20
7788 SCOTT ANALYST 7566 13-7月 -87 3000 20
7876 ADAMS CLERK 7788 13-7月 -87 1100 20
7902 FORD ANALYST 7566 03-12月-81 3000 20
SQL> host cls
any与all查询
any
SQL> --any: 集合中的任意一个
SQL> --查询工资比20号部门任意员工工资高的员工信息
SQL> select *
2 from emp
3 where sal > any (select sal from emp where deptno=20);
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 13-7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 13-7月 -87 1100 20
7900 JAMES CLERK 7698 03-12月-81 950 30
已选择13行。
SQL> ed
已写入 file afiedt.buf
1 select *
2 from emp
3* where sal > any (select sal from emp where deptno=10)
SQL> /
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 13-7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
已选择8行。
all
SQL> --all:和集合的所有值比
SQL> --查询工资比20号部门所有员工工资高的员工信息
SQL> select *
2 from emp\
3 ;
from emp\
*
第 2 行出现错误:
ORA-00911: 无效字符
SQL> select *
2 from emp
3 where sal > all (select sal from emp where deptno=20);
EMPNO ENAME JOB MGR HIREDATE SAL C