SQL SERVER – Disable All the Foreign Key Constraint in Database – Enable All the Foreign Key Constraint in Database

-- Disable all the constraint in database

EXEC sp_msforeachtable "ALTER TABLE ? NOCHECK CONSTRAINT all"

-- Enable all the constraint in database

EXEC sp_msforeachtable "ALTER TABLE ? WITH CHECK CHECK CONSTRAINT all"

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SQL SERVER – Create Unique Constraint on Table Column on Existing Table

by using UNIQUE for Unique constraint.

Syntax:

   UNIQUE([col name])

Example:

USE tempdb
GO
-- Create Table
CREATE TABLE Table1 (ID INT, Col1 VARCHAR(100))
GO
-- Alter Table Create Constraint
ALTER TABLE Table1
ADD CONSTRAINT UX_Constraint UNIQUE (Col1)
GO
-- Clean up
DROP TABLE Table1
GO