Question

Possible Duplicate:
How to enforce a constraint of foreign key on columns of same table in SQL

Table1

Column1 Column2  Column3 
 1        value  1
 2        value  1
 3        value  2

here in a same table column 1 is primary key, but column3 value must be from column1.
How to create table like this.

Answer 1

If your table is already there then you need to run couple of ddl statements

CREATE TABLE TABLE_1 
    ( 
     column1 NUMBER (4)  NOT NULL , 
     column2 VARCHAR2(20)  NOT NULL , 
     column3 NUMBER (4) 
    ) 
;


ALTER TABLE TABLE_1 
    ADD CONSTRAINT TABLE_1_PK PRIMARY KEY ( column1) ;



ALTER TABLE TABLE_1 
    ADD CONSTRAINT TABLE_1_TABLE_1_FK FOREIGN KEY 
    ( 

     column3
    ) 
    REFERENCES TABLE_1 
    ( 
     column1
    ) 
;