Oracle DROP foreign key.

Preamble

After creating a foreign key, you may need to drop the foreign key from the table. You can do this with the ALTER TABLE operator in Oracle/PLSQL.

Syntax to drop a foreign key in Oracle / PLSQL

ALTER TABLE table_name
DROP CONSTRAINT constraint_name;

Example

If you created a foreign key like this:

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 created the primary key table of the supplier called supplier_pk.

It consists of only one supplier_id field. Then we created a foreign key named fk_supplier in the products table that refers to the supplier table based on the supplier_id field.

If we need to drop the foreign key named fk_supplier, we need to execute the following command:

ALTER TABLE products
DROP CONSTRAINT fk_supplier;

SQL tutorials: SQL Foreign Key Constraint

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