sec@ora10g> create table test1 ( a number primary key, b number not null);
Table created.
sec@ora10g> desc test1;
Name Null? Type
---------------------- -------- ------------------
A NOT NULL NUMBER
B NOT NULL NUMBER
sec@ora10g> insert into test1 values (1,1);
1 row created.
sec@ora10g> insert into test1 values (2,2);
1 row created.
sec@ora10g> COMMIT;
Commit complete.
sec@ora10g> create table test2 as select * from test1;
Table created.
sec@ora10g> desc test2;
Name Null? Type
--------------------- -------- ------------------
A NUMBER
B NOT NULL NUMBER
sec@ora10g> select * from test1;
A B
---------- ----------
1 1
2 2
sec@ora10g> select * from test2;
A B
---------- ----------
1 1
2 2
分享题目：【实验】验证通过createtableasselect方式无法创建主键小实验
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