In this article, we will talk about CHECK constraints. We will see how to add CHECK constraints to SQL Server table columns and discuss the pitfalls you may encounter when using this type of SQL Server constraints.
CHECK constraint basics
CHECK constraints are simply conditional statements (predicates that return TRUE or FALSE) that refer to table columns for maintaining data integrity. When one inserts data into a column or several columns in a single row, CHECK constraints come into action. They evaluate the data to be inserted. In case the data does not meet the condition specified in the CHECK constraint, the insertion fails.