Re: Key field in a table?

On 19 Jan 1999 20:16:58 GMT, sjx_at_peon.rightiming.com (Sheng Juexin) wrote:

>I want to create a table with a field "User_Id". I want "User_Id" to be the key
>to distinguish different rows in the table. If I insert a new row with the same
>"Uer_Id" value, the Oracle should refuse to insert the now row. Can I define
>such a kind of table?
>
>Thank you!

You want to define that column as the primary key.

eg.

SQL> create table mytable(
  2 user_id number primary key,
  3 name varchar2(30) );
Table created.

SQL> insert into mytable values ( 1, 'Chris' ); 1 row created.

SQL> insert into mytable values ( 2, 'Tom' ); 1 row created.

SQL> insert into mytable values ( 1, 'Joel' ); insert into mytable values ( 1, 'Joel' )

            *
ERROR at line 1:
ORA-00001: unique constraint (CLBECK.SYS_C0034782) violated

SQL> select * from mytable;

   USER_ID NAME

---------- ------------------------------
         1 Chris
         2 Tom

Hope this helps.

chris.

>
>sjx

--
Christopher Beck
Oracle Corporation
clbeck_at_us.oracle.com
Reston, VA.
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