Oracle / PLSQL: Disable a foreign key

This Oracle tutorial explains how to disable a foreign key in Oracle with syntax and examples.

Description

Once you have created a foreign key in Oracle, you may encounter a situation where you are required to disable the foreign key. You can do this using the ALTER TABLE statement in Oracle.

Syntax

The syntax to disable a foreign key in Oracle/PLSQL is:

ALTER TABLE table_name
DISABLE CONSTRAINT constraint_name;

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 we then wanted to disable the foreign key called fk_supplier, we could execute the following command:

ALTER TABLE products
DISABLE CONSTRAINT fk_supplier;