Jan 30, 2025 · In this article, we will explain the most common SQL constraints in detail, providing clear examples and explaining how to implement them effectively. What Are SQL Constraints?

Constraints can be column level or table level. Column level constraints apply to a column, and table level constraints apply to the whole table. The following constraints are commonly used …

Sep 22, 2025 · Explore Key Constraints in SQL with practical examples, and understand how they ensure data integrity and prevent errors in relational databases.

Feb 8, 2023 · In this SQL tutorial, we’ll demonstrate examples for the types of constraints that can be created in Microsoft SQL Server. The T-SQL constraint code can be copied, pasted, and …

To learn more, visit SQL UNIQUE Constraint. The PRIMARY KEY constraint is simply a combination of NOT NULL and UNIQUE constraints. It means that the column value is used to …

Nov 18, 2025 · Primary keys and foreign keys are two types of constraints that can be used to enforce data integrity in SQL Server tables. These are important database objects. A table …

Here are the key types of constraints available in SQL Server: PRIMARY KEY Constraint: The PRIMARY KEY constraint uniquely identifies each record in a table. No two rows can have the …

Sep 11, 2025 · Constraints are checked on writes (INSERT, UPDATE, DELETE); if a write would violate a constraint, the statement fails and no changes are applied. In this note we’ll discuss …

Jul 19, 2025 · SQL Constraints are rules enforced on data columns in a database table. They help ensure the accuracy, consistency, and reliability of the data stored in a database.