Oracle/PLSQL: Enable a foreign key

The syntax for enabling a foreign key is:

ALTER TABLE table_name

enable CONSTRAINT constraint_name;

For example:

If you had created a foreign key as follows:

CREATE TABLE supplier

( supplier_id numeric(10) not null,

supplier_name varchar2(50) not null,

contact_name varchar2(50),

CONSTRAINT supplier_pk PRIMARY KEY

(supplier_id)

);

CREATE TABLE products

( product_id numeric(10) not null,

supplier_id numeric(10) not null,

CONSTRAINT fk_supplier

FOREIGN KEY (supplier_id)

REFERENCES supplier(supplier_id)

);

In this example, we've created a primary key on the supplier table called

supplier_pk. It consists of only one field - the supplier_id field. Then we've created a foreign key called fk_supplier on the products table that references the supplier table based on the supplier_id field.

If the foreign key had been disabled and we wanted to enable it, we could execute the following command:

ALTER TABLE products

enable CONSTRAINT fk_supplier; Download Here Click Here