CREATE TABLE 表名 AS SELECT 语句

Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.1.0
Connected as scott

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 SQL> select * from dept; DEPTNO DNAME          LOC------ -------------- -------------    10 ACCOUNTING     NEW YORK    20 RESEARCH       DALLAS    30 SALES          CHICAGO    40 OPERATIONS     BOSTON SQL> create table dept2 as select * from dept; Table created SQL> select * from dept; DEPTNO DNAME          LOC------ -------------- -------------    10 ACCOUNTING     NEW YORK    20 RESEARCH       DALLAS    30 SALES          CHICAGO    40 OPERATIONS     BOSTON SQL> select * from dept2; DEPTNO DNAME          LOC------ -------------- -------------    10 ACCOUNTING     NEW YORK    20 RESEARCH       DALLAS    30 SALES          CHICAGO    40 OPERATIONS     BOSTONSQL> create table dept3 as select * from dept where 1 = 2; Table created SQL> select * from dept3; DEPTNO DNAME          LOC------ -------------- ------------- SQL> select OWNER from user_constraints where table_name = 'DEPT'; OWNER--------------------------------------------SCOTT SQL> select OWNER from user_constraints where table_name = 'DEPT2'; OWNER-------------------------------------------- 

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由上面的使用 CREATE TABLE 表名 AS SELECT 语句可以看出：

??? 1：只会复制表数据和表结构，不会有任何约束。

??? 2：当 where 条件不成立时，只复制表结构，没有任务数据。