The ADD CONSTRAINT command is used to create a constraint after a table is already created. The following SQL adds a constraint named "PK_Person" that is a PRIMARY KEY constraint on …

Jan 6, 2026 · Constraints can be specified during the table creation process using the CREATE TABLE statement. Additionally, constraints can be modified or added to existing tables using the ALTER …

Jan 11, 2024 · This recipe will guide you through the journey into what SQL constraints are, the various types of SQL constraints, and practical examples and usage scenarios to help you understand how …

Jun 29, 2023 · Learn how to use ADD CONSTRAINT to manage primary keys, foreign keys, and other constraints in SQL databases.

Learn how to add constraints in SQL to enforce data integrity. This guide covers primary, unique, check, and foreign key constraints with examples.

We can add constraints using ALTER TABLE Statement followed by ADD CONSTRAINT Command. Most used syntaxes for ADD CONSTRAINTs on existing table are listed as below -

A unique constraint ensures that all values in a column (or a set of columns) are unique. To add a unique constraint, you use the ALTER TABLE statement with the ADD keyword and the UNIQUE …

How do you add, drop, and rename constraints in SQL? In this video, we'll take a look at how to use ADD CONSTRAINT, DROP CONSTRAINT, and RENAME CONSTRAINT.

Nov 18, 2025 · SQL Server 2022 (16.x) introduces resumable operations for adding table constraints for primary key and unique key constraints. For more information on enabling and using resumable …

Oct 12, 2024 · Learn how to use SQL ALTER TABLE ADD CONSTRAINT to enforce data integrity.