[转]oracle 同义词 synonym

本文转自：http://blog.csdn.net/generalfu/article/details/7906561

同义词定义 当一个用户想访问另外一个用户的表时， 需要在表前加用户名，总加表名不方便， 为此可以为用户名、表名起个小名别名， 以方便访问，此别名就是同义词。
创建同义词 create synonym  同义词名  for 用户名.表名称;

删除同义词 drop  synonym  syn_name;

测试实例 --没有创建同义词之前

SQL> select * from scott.emp where deptno = 10;

EMPNO ENAME      JOB         MGR HIREDATE          SAL      COMM DEPTNO
----- ---------- --------- ----- ----------- --------- --------- ------
 7782 CLARK      MANAGER    7839 1981-6-9      2450.00               10
 7839 KING       PRESIDENT       1981-11-17    5000.00               10
 7934 MILLER     CLERK      7782 1982-1-23     1300.00               10

Executed in 0.078 seconds

SQL> select * from scott.emp where deptno = 10;
 
EMPNO ENAME      JOB         MGR HIREDATE          SAL      COMM DEPTNO
----- ---------- --------- ----- ----------- --------- --------- ------
 7782 CLARK      MANAGER    7839 1981-6-9      2450.00               10
 7839 KING       PRESIDENT       1981-11-17    5000.00               10
 7934 MILLER     CLERK      7782 1982-1-23     1300.00               10
 
Executed in 0.078 seconds

--创建同义词

SQL> create synonym myemp for scott.emp;

Synonym created

Executed in 0.265 seconds

SQL> create synonym myemp for scott.emp;
 
Synonym created
 
Executed in 0.265 seconds

--使用同义词

SQL> select * from myemp where deptno = 10;

EMPNO ENAME      JOB         MGR HIREDATE          SAL      COMM DEPTNO
----- ---------- --------- ----- ----------- --------- --------- ------
 7782 CLARK      MANAGER    7839 1981-6-9      2450.00               10
 7839 KING       PRESIDENT       1981-11-17    5000.00               10
 7934 MILLER     CLERK      7782 1982-1-23     1300.00               10

Executed in 0.047 seconds