Primary KEY by Query

[Guest tao]

Hi ,how can i get from specific table the Primary Key field name, by SQL Query?thanks,Tao

[aspnetguy]

I don't think you can.Why do you need to?

[sivasairam]

SELECT COLUMN_NAME FROM USER_CONS_COLUMNS WHERE CONSTRAINT_NAME = (SELECT CONSTRAINT_NAME FROM ALL_CONSTRAINTS WHERE CONSTRAINT_TYPE IN ('P') AND TABLE_NAME =<TABLE_NAME>)I think this will help you...Sairam

[rawr215]

I just did my sql homework and i had to do the same thing i found this site was useful:http://www.cs.wisc.edu/~dbbook/openAccess/...e_guide.html#oc

Observing ConstraintsOften you may wish to see what constraints exist on a table. The view USER_CONSTRAINTS is maintained by Oracle and has information about constraints. Some interesting columns include, the CONSTRAINT_NAME, CONSTRAINT_TYPE where P refers to primary key, and R is a foreign key constraints, the TABLE_NAME on which it is defined, and the R_CONSTRAINT_NAME for foreign key constraints. Type DESCRIBE USER_CONSTRAINTS for more informaion.Once you know the CONSTRAINT_NAME, you can use the USER_CONS_COLUMNS view to find the COLUMN_NAME and POSITION for that CONSTRAINT_NAME. You can query these views as you would any other table:select column_name, position, constraint_name from User_cons_columns;