ORACLE-多表关联
2016-01-10 20:09
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1、交叉连接（cross
join）
CROSSJOIN连接用于生成两张表的笛卡尔集。
在sql中cross join的使用：
1）返回的记录数为两个表的记录数乘积。
2）将A表的所有行分别与B表的所有行进行连接。
结果表：
列=
原表列数相加
行=
原表行数相乘
SQL> select *from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
----- ------------------- ----- ----------- --------- --------- ------
7369 SMITH CLERK 7902 1980/12/17 800.00 20
7499 ALLEN SALESMAN 7698 1981/2/20 1760.00 300.00 30
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30
7566 JONES MANAGER 7839 1981/4/2 2975.00 20
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20
7839 KING PRESIDENT 1981/11/17 5000.00 10
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30
7876 ADAMS CLERK 7788 1987/5/23 1100.00 20
7900 JAMES CLERK 7698 1981/12/3 950.00 30
7902 FORD ANALYST 7566 1981/12/3 3000.00 20
7934 MILLER CLERK 7782 1982/1/23 1300.00 10
8888 测试数据 旺旺 1888 1982/1/23 1300.00 10
15 rows selected
SQL> select *from dept;
DEPTNO DNAME LOC
-------------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
SQL> select *from emp a cross join dept;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO DEPTNO DNAME LOC
----- ------------------- ----- ----------- --------- --------- ------ ------ ---------------------------
7369 SMITH CLERK 7902 1980/12/17 800.00 20 10 ACCOUNTING NEW YORK
7499 ALLEN SALESMAN 7698 1981/2/20 1760.00 300.00 30 10 ACCOUNTING NEW YORK
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30 10 ACCOUNTING NEW YORK
7566 JONES MANAGER 7839 1981/4/2 2975.00 20 10 ACCOUNTING NEW YORK
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30 10 ACCOUNTING NEW YORK
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30 10 ACCOUNTING NEW YORK
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10 10 ACCOUNTING NEW YORK
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20 10 ACCOUNTING NEW YORK
7839 KING PRESIDENT 1981/11/17 5000.00 10 10 ACCOUNTING NEW YORK
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30 10 ACCOUNTING NEW YORK
7876 ADAMS CLERK 7788 1987/5/23 1100.00 20 10 ACCOUNTING NEW YORK
7900 JAMES CLERK 7698 1981/12/3 950.00 30 10 ACCOUNTING NEW YORK
7902 FORD ANALYST 7566 1981/12/3 3000.00 20 10 ACCOUNTING NEW YORK
7934 MILLER CLERK 7782 1982/1/23 1300.00 10 10 ACCOUNTING NEW YORK
8888 测试数据 旺旺 1888 1982/1/23 1300.00 10 10 ACCOUNTING NEW YORK
7369 SMITH CLERK 7902 1980/12/17 800.00 20 20 RESEARCH DALLAS
7499 ALLEN SALESMAN 7698 1981/2/20 1760.00 300.00 30 20 RESEARCH DALLAS
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30 20 RESEARCH DALLAS
7566 JONES MANAGER 7839 1981/4/2 2975.00 20 20 RESEARCH DALLAS
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30 20 RESEARCH DALLAS
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO DEPTNO DNAME LOC
----- ------------------- ----- ----------- --------- --------- ------ ------ ---------------------------
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30 20 RESEARCH DALLAS
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10 20 RESEARCH DALLAS
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20 20 RESEARCH DALLAS
7839 KING PRESIDENT 1981/11/17 5000.00 10 20 RESEARCH DALLAS
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30 20 RESEARCH DALLAS
7876 ADAMS CLERK 7788 1987/5/23 1100.00 20 20 RESEARCH DALLAS
7900 JAMES CLERK 7698 1981/12/3 950.00 30 20 RESEARCH DALLAS
7902 FORD ANALYST 7566 1981/12/3 3000.00 20 20 RESEARCH DALLAS
7934 MILLER CLERK 7782 1982/1/23 1300.00 10 20 RESEARCH DALLAS
8888 测试数据 旺旺 1888 1982/1/23 1300.00 10 20 RESEARCH DALLAS
7369 SMITH CLERK 7902 1980/12/17 800.00 20 30 SALES CHICAGO
7499 ALLEN SALESMAN 7698 1981/2/20 1760.00 300.00 30 30 SALES CHICAGO
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30 30 SALES CHICAGO
7566 JONES MANAGER 7839 1981/4/2 2975.00 20 30 SALES CHICAGO
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30 30 SALES CHICAGO
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30 30 SALES CHICAGO
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10 30 SALES CHICAGO
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20 30 SALES CHICAGO
7839 KING PRESIDENT 1981/11/17 5000.00 10 30 SALES CHICAGO
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30 30 SALES CHICAGO
7876 ADAMS CLERK 7788 1987/5/23 1100.00 20 30 SALES CHICAGO
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO DEPTNO DNAME LOC
----- ------------------- ----- ----------- --------- --------- ------ ------ ---------------------------
7900 JAMES CLERK 7698 1981/12/3 950.00 30 30 SALES CHICAGO
7902 FORD ANALYST 7566 1981/12/3 3000.00 20 30 SALES CHICAGO
7934 MILLER CLERK 7782 1982/1/23 1300.00 10 30 SALES CHICAGO
8888 测试数据 旺旺 1888 1982/1/23 1300.00 10 30 SALES CHICAGO
7369 SMITH CLERK 7902 1980/12/17 800.00 20 40 OPERATIONS BOSTON
7499 ALLEN SALESMAN 7698 1981/2/20 1760.00 300.00 30 40 OPERATIONS BOSTON
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30 40 OPERATIONS BOSTON
7566 JONES MANAGER 7839 1981/4/2 2975.00 20 40 OPERATIONS BOSTON
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30 40 OPERATIONS BOSTON
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30 40 OPERATIONS BOSTON
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10 40 OPERATIONS BOSTON
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20 40 OPERATIONS BOSTON
7839 KING PRESIDENT 1981/11/17 5000.00 10 40 OPERATIONS BOSTON
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30 40 OPERATIONS BOSTON
7876 ADAMS CLERK 7788 1987/5/23 1100.00 20 40 OPERATIONS BOSTON
7900 JAMES CLERK 7698 1981/12/3 950.00 30 40 OPERATIONS BOSTON
7902 FORD ANALYST 7566 1981/12/3 3000.00 20 40 OPERATIONS BOSTON
7934 MILLER CLERK 7782 1982/1/23 1300.00 10 40 OPERATIONS BOSTON
8888 测试数据 旺旺 1888 1982/1/23 1300.00 10 40 OPERATIONS BOSTON
60 rows selected
select * from emp a cross join dept;的运行机制是首先将a表中的所有记录逐条查出，然后与dept表中的每一行分别进行组合。
2、内连接--inner
join（join）
SQL> select *from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
----- ------------------- ----- ----------- --------- --------- ------
7369 SMITH CLERK 7902 1980/12/17 800.00 20
7499 ALLEN SALESMAN 7698 1981/2/20 1760.00 300.00 30
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30
7566 JONES MANAGER 7839 1981/4/2 2975.00 20
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20
7839 KING PRESIDENT 1981/11/17 5000.00 10
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30
7876 ADAMS CLERK 7788 1987/5/23 1100.00 20
7900 JAMES CLERK 7698 1981/12/3 950.00 30
7902 FORD ANALYST 7566 1981/12/3 3000.00 20
7934 MILLER CLERK 7782 1982/1/23 1300.00 10
8888 测试数据 旺旺 1888 1982/1/23 1300.00 10
15 rows selected
SQL> select *from dept;
DEPTNO DNAME LOC
-------------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
de8c
30 SALES CHICAGO
40 OPERATIONS BOSTON
SQL> selecta.empno,a.ename,b.deptno,b.dname from emp a inner join dept b ona.deptno=b.deptno;
EMPNO ENAME DEPTNO DNAME
----- ---------------- --------------
7782 CLARK 10 ACCOUNTING
8888 测试数据 10 ACCOUNTING
7839 KING 10 ACCOUNTING
7934 MILLER 10 ACCOUNTING
7566 JONES 20 RESEARCH
7369 SMITH 20 RESEARCH
7788 SCOTT 20 RESEARCH
7902 FORD 20 RESEARCH
7876 ADAMS 20 RESEARCH
7844 TURNER 30 SALES
7499 ALLEN 30 SALES
7900 JAMES 30 SALES
7521 WARD 30 SALES
7654 MARTIN 30 SALES
7698 BLAKE 30 SALES
15 rows selected
3、外连接--outer
join（左连接、右连接、全连接）
1）左连接（left join）
2）右连接（right join）
3）全连接（full join）
语法：
内连接--inner join
（join）
也可叫做等值连接
1）select a.empno,a.ename,b.deptno from empa,dept b where a.deptno=b.deptno
and a.deptno>20;---等值连接
EMPNO ENAME DEPTNO
----- ----------------
7499 ALLEN 30
7521 WARD 30
7654 MARTIN 30
7698 BLAKE 30
7844 TURNER 30
7900 JAMES 30
2）select a.empno,a.ename,b.deptno from empa
（inner）joindept b on a.deptno=b.deptno and
a.deptno>20;---内连接
EMPNO ENAME DEPTNO
----- ----------------
7499 ALLEN 30
7521 WARD 30
7654 MARTIN 30
7698 BLAKE 30
7844 TURNER 30
7900 JAMES 30
外连接--outer join
3）左连接--left
join
selecta.empno,a.ename,b.deptno from emp a left join dept b on a.deptno=b.deptno anda.deptno=20;
EMPNO ENAME DEPTNO
----- ----------------
7369 SMITH 20
7499 ALLEN
7521 WARD
7566 JONES 20
7654 MARTIN
7698 BLAKE
7782 CLARK
7788 SCOTT 20
7839 KING
7844 TURNER
7876 ADAMS 20
7900 JAMES
7902 FORD 20
7934 MILLER
8888 测试数据
selecta.empno,a.ename,b.deptno from emp a left join dept b on a.deptno=b.deptno;
等价于
selecta.empno,a.ename,b.deptno from emp a , dept b where a.deptno=b.deptno(+);
EMPNO ENAME DEPTNO
----- ----------------
7369 SMITH 20
7499 ALLEN 30
7521 WARD 30
7566 JONES 20
7654 MARTIN 30
7698 BLAKE 30
7782 CLARK 10
7788 SCOTT 20
7839 KING 10
7844 TURNER 30
7876 ADAMS 20
7900 JAMES 30
7902 FORD 20
7934 MILLER 10
8888 测试数据 10
4）右连接--right join
selecta.empno,a.ename,b.deptno from emp a right join dept b on a.deptno=b.deptno;
等价于
selecta.empno,a.ename,b.deptno from emp a , dept b where a.deptno(+)=b.deptno;
EMPNO ENAME DEPTNO
----- ----------------
7369 SMITH 20
7499 ALLEN 30
7521 WARD 30
7566 JONES 20
7654 MARTIN 30
7698 BLAKE 30
7782 CLARK 10
7788 SCOTT 20
7839 KING 10
7844 TURNER 30
7876 ADAMS 20
7900 JAMES 30
7902 FORD 20
7934 MILLER 10
8888 测试数据 10
40
5）全连接--full join
selecta.empno,a.ename,b.deptno from emp a full join dept b on a.deptno=b.deptno;
join）
CROSSJOIN连接用于生成两张表的笛卡尔集。
在sql中cross join的使用：
1）返回的记录数为两个表的记录数乘积。
2）将A表的所有行分别与B表的所有行进行连接。
结果表：
列=
原表列数相加
行=
原表行数相乘
SQL> select *from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
----- ------------------- ----- ----------- --------- --------- ------
7369 SMITH CLERK 7902 1980/12/17 800.00 20
7499 ALLEN SALESMAN 7698 1981/2/20 1760.00 300.00 30
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30
7566 JONES MANAGER 7839 1981/4/2 2975.00 20
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20
7839 KING PRESIDENT 1981/11/17 5000.00 10
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30
7876 ADAMS CLERK 7788 1987/5/23 1100.00 20
7900 JAMES CLERK 7698 1981/12/3 950.00 30
7902 FORD ANALYST 7566 1981/12/3 3000.00 20
7934 MILLER CLERK 7782 1982/1/23 1300.00 10
8888 测试数据 旺旺 1888 1982/1/23 1300.00 10
15 rows selected
SQL> select *from dept;
DEPTNO DNAME LOC
-------------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
SQL> select *from emp a cross join dept;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO DEPTNO DNAME LOC
----- ------------------- ----- ----------- --------- --------- ------ ------ ---------------------------
7369 SMITH CLERK 7902 1980/12/17 800.00 20 10 ACCOUNTING NEW YORK
7499 ALLEN SALESMAN 7698 1981/2/20 1760.00 300.00 30 10 ACCOUNTING NEW YORK
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30 10 ACCOUNTING NEW YORK
7566 JONES MANAGER 7839 1981/4/2 2975.00 20 10 ACCOUNTING NEW YORK
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30 10 ACCOUNTING NEW YORK
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30 10 ACCOUNTING NEW YORK
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10 10 ACCOUNTING NEW YORK
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20 10 ACCOUNTING NEW YORK
7839 KING PRESIDENT 1981/11/17 5000.00 10 10 ACCOUNTING NEW YORK
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30 10 ACCOUNTING NEW YORK
7876 ADAMS CLERK 7788 1987/5/23 1100.00 20 10 ACCOUNTING NEW YORK
7900 JAMES CLERK 7698 1981/12/3 950.00 30 10 ACCOUNTING NEW YORK
7902 FORD ANALYST 7566 1981/12/3 3000.00 20 10 ACCOUNTING NEW YORK
7934 MILLER CLERK 7782 1982/1/23 1300.00 10 10 ACCOUNTING NEW YORK
8888 测试数据 旺旺 1888 1982/1/23 1300.00 10 10 ACCOUNTING NEW YORK
7369 SMITH CLERK 7902 1980/12/17 800.00 20 20 RESEARCH DALLAS
7499 ALLEN SALESMAN 7698 1981/2/20 1760.00 300.00 30 20 RESEARCH DALLAS
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30 20 RESEARCH DALLAS
7566 JONES MANAGER 7839 1981/4/2 2975.00 20 20 RESEARCH DALLAS
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30 20 RESEARCH DALLAS
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO DEPTNO DNAME LOC
----- ------------------- ----- ----------- --------- --------- ------ ------ ---------------------------
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30 20 RESEARCH DALLAS
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10 20 RESEARCH DALLAS
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20 20 RESEARCH DALLAS
7839 KING PRESIDENT 1981/11/17 5000.00 10 20 RESEARCH DALLAS
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30 20 RESEARCH DALLAS
7876 ADAMS CLERK 7788 1987/5/23 1100.00 20 20 RESEARCH DALLAS
7900 JAMES CLERK 7698 1981/12/3 950.00 30 20 RESEARCH DALLAS
7902 FORD ANALYST 7566 1981/12/3 3000.00 20 20 RESEARCH DALLAS
7934 MILLER CLERK 7782 1982/1/23 1300.00 10 20 RESEARCH DALLAS
8888 测试数据 旺旺 1888 1982/1/23 1300.00 10 20 RESEARCH DALLAS
7369 SMITH CLERK 7902 1980/12/17 800.00 20 30 SALES CHICAGO
7499 ALLEN SALESMAN 7698 1981/2/20 1760.00 300.00 30 30 SALES CHICAGO
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30 30 SALES CHICAGO
7566 JONES MANAGER 7839 1981/4/2 2975.00 20 30 SALES CHICAGO
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30 30 SALES CHICAGO
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30 30 SALES CHICAGO
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10 30 SALES CHICAGO
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20 30 SALES CHICAGO
7839 KING PRESIDENT 1981/11/17 5000.00 10 30 SALES CHICAGO
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30 30 SALES CHICAGO
7876 ADAMS CLERK 7788 1987/5/23 1100.00 20 30 SALES CHICAGO
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO DEPTNO DNAME LOC
----- ------------------- ----- ----------- --------- --------- ------ ------ ---------------------------
7900 JAMES CLERK 7698 1981/12/3 950.00 30 30 SALES CHICAGO
7902 FORD ANALYST 7566 1981/12/3 3000.00 20 30 SALES CHICAGO
7934 MILLER CLERK 7782 1982/1/23 1300.00 10 30 SALES CHICAGO
8888 测试数据 旺旺 1888 1982/1/23 1300.00 10 30 SALES CHICAGO
7369 SMITH CLERK 7902 1980/12/17 800.00 20 40 OPERATIONS BOSTON
7499 ALLEN SALESMAN 7698 1981/2/20 1760.00 300.00 30 40 OPERATIONS BOSTON
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30 40 OPERATIONS BOSTON
7566 JONES MANAGER 7839 1981/4/2 2975.00 20 40 OPERATIONS BOSTON
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30 40 OPERATIONS BOSTON
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30 40 OPERATIONS BOSTON
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10 40 OPERATIONS BOSTON
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20 40 OPERATIONS BOSTON
7839 KING PRESIDENT 1981/11/17 5000.00 10 40 OPERATIONS BOSTON
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30 40 OPERATIONS BOSTON
7876 ADAMS CLERK 7788 1987/5/23 1100.00 20 40 OPERATIONS BOSTON
7900 JAMES CLERK 7698 1981/12/3 950.00 30 40 OPERATIONS BOSTON
7902 FORD ANALYST 7566 1981/12/3 3000.00 20 40 OPERATIONS BOSTON
7934 MILLER CLERK 7782 1982/1/23 1300.00 10 40 OPERATIONS BOSTON
8888 测试数据 旺旺 1888 1982/1/23 1300.00 10 40 OPERATIONS BOSTON
60 rows selected
select * from emp a cross join dept;的运行机制是首先将a表中的所有记录逐条查出，然后与dept表中的每一行分别进行组合。
2、内连接--inner
join（join）
SQL> select *from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
----- ------------------- ----- ----------- --------- --------- ------
7369 SMITH CLERK 7902 1980/12/17 800.00 20
7499 ALLEN SALESMAN 7698 1981/2/20 1760.00 300.00 30
7521 WARD SALESMAN 7698 1981/2/22 1250.00 500.00 30
7566 JONES MANAGER 7839 1981/4/2 2975.00 20
7654 MARTIN SALESMAN 7698 1981/9/28 1250.00 1400.00 30
7698 BLAKE MANAGER 7839 1981/5/1 2850.00 30
7782 CLARK MANAGER 7839 1981/6/9 2450.00 10
7788 SCOTT ANALYST 7566 1987/4/19 3000.00 20
7839 KING PRESIDENT 1981/11/17 5000.00 10
7844 TURNER SALESMAN 7698 1981/9/8 1500.00 0.00 30
7876 ADAMS CLERK 7788 1987/5/23 1100.00 20
7900 JAMES CLERK 7698 1981/12/3 950.00 30
7902 FORD ANALYST 7566 1981/12/3 3000.00 20
7934 MILLER CLERK 7782 1982/1/23 1300.00 10
8888 测试数据 旺旺 1888 1982/1/23 1300.00 10
15 rows selected
SQL> select *from dept;
DEPTNO DNAME LOC
-------------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
de8c
30 SALES CHICAGO
40 OPERATIONS BOSTON
SQL> selecta.empno,a.ename,b.deptno,b.dname from emp a inner join dept b ona.deptno=b.deptno;
EMPNO ENAME DEPTNO DNAME
----- ---------------- --------------
7782 CLARK 10 ACCOUNTING
8888 测试数据 10 ACCOUNTING
7839 KING 10 ACCOUNTING
7934 MILLER 10 ACCOUNTING
7566 JONES 20 RESEARCH
7369 SMITH 20 RESEARCH
7788 SCOTT 20 RESEARCH
7902 FORD 20 RESEARCH
7876 ADAMS 20 RESEARCH
7844 TURNER 30 SALES
7499 ALLEN 30 SALES
7900 JAMES 30 SALES
7521 WARD 30 SALES
7654 MARTIN 30 SALES
7698 BLAKE 30 SALES
15 rows selected
3、外连接--outer
join（左连接、右连接、全连接）
1）左连接（left join）
2）右连接（right join）
3）全连接（full join）
语法：
内连接--inner join
（join）
也可叫做等值连接
1）select a.empno,a.ename,b.deptno from empa,dept b where a.deptno=b.deptno
and a.deptno>20;---等值连接
EMPNO ENAME DEPTNO
----- ----------------
7499 ALLEN 30
7521 WARD 30
7654 MARTIN 30
7698 BLAKE 30
7844 TURNER 30
7900 JAMES 30
2）select a.empno,a.ename,b.deptno from empa
（inner）joindept b on a.deptno=b.deptno and
a.deptno>20;---内连接
EMPNO ENAME DEPTNO
----- ----------------
7499 ALLEN 30
7521 WARD 30
7654 MARTIN 30
7698 BLAKE 30
7844 TURNER 30
7900 JAMES 30
外连接--outer join
3）左连接--left
join
selecta.empno,a.ename,b.deptno from emp a left join dept b on a.deptno=b.deptno anda.deptno=20;
EMPNO ENAME DEPTNO
----- ----------------
7369 SMITH 20
7499 ALLEN
7521 WARD
7566 JONES 20
7654 MARTIN
7698 BLAKE
7782 CLARK
7788 SCOTT 20
7839 KING
7844 TURNER
7876 ADAMS 20
7900 JAMES
7902 FORD 20
7934 MILLER
8888 测试数据
selecta.empno,a.ename,b.deptno from emp a left join dept b on a.deptno=b.deptno;
等价于
selecta.empno,a.ename,b.deptno from emp a , dept b where a.deptno=b.deptno(+);
EMPNO ENAME DEPTNO
----- ----------------
7369 SMITH 20
7499 ALLEN 30
7521 WARD 30
7566 JONES 20
7654 MARTIN 30
7698 BLAKE 30
7782 CLARK 10
7788 SCOTT 20
7839 KING 10
7844 TURNER 30
7876 ADAMS 20
7900 JAMES 30
7902 FORD 20
7934 MILLER 10
8888 测试数据 10
4）右连接--right join
selecta.empno,a.ename,b.deptno from emp a right join dept b on a.deptno=b.deptno;
等价于
selecta.empno,a.ename,b.deptno from emp a , dept b where a.deptno(+)=b.deptno;
EMPNO ENAME DEPTNO
----- ----------------
7369 SMITH 20
7499 ALLEN 30
7521 WARD 30
7566 JONES 20
7654 MARTIN 30
7698 BLAKE 30
7782 CLARK 10
7788 SCOTT 20
7839 KING 10
7844 TURNER 30
7876 ADAMS 20
7900 JAMES 30
7902 FORD 20
7934 MILLER 10
8888 测试数据 10
40
5）全连接--full join
selecta.empno,a.ename,b.deptno from emp a full join dept b on a.deptno=b.deptno;
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