![]() ![]() For instance, say I want to ensure that when I enter an “Hourly” SalaryType, I want the Salary to be less than $100.00 or when “Monthly” SalaryType is entered the Salary is not over $10,000, and when an “Annual” SalaryType is enter then any Salary amount is fine. Keep in mind when you do this it will be more difficult to understand whether it was the SalaryType, Salary, or both columns that violated your check constraint.Īnother twist on the prior example is to use the value in more than one column to determine whether a specific column value is valid. This single constraint does the same thing as the above two constraints. ![]() The logical expression may be a single expression like “Salary GETDATE() and RentalDate 10.00 and Salary 10.00 and Salary 10.00 and Salary 10.00 and Salary < 150000.00) If data being inserted or updated violates a check constraint the database engine will not allow the INSERT or UPDATE operation to occur.Ī check constraint consists of a logical expression to identify what is a valid expression. You can have multiple check constraint for a single column. A check constraint can validate the domain integrity of a single column or a number of columns. Domain integrity defines the valid values for columns within a database table. Check constraints help enforce domain integrity. What is a check constraint?Ī check constraint is a rule that identifies acceptable column values for data in a row within a SQL Server table. In this article, I’m going to discuss how you can use database “check constraints” to validate your data within the SQL Server database engine. Depending on your validation, rule requirement will determine where and how you will need to build your application to ensure your data is properly validated. Data validate rules can be enforced within your application code in the application layer or data can be validated by the database engine. There are a number of different processes that can be used to make sure your data validates against your business rules. Data validation is a critical part of your application to ensure your data meets the requirements developed by your business analysts. One of the key goals when building applications is to make sure the data you enter into the database meets all your business rules.
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