What are the best practices for naming and documenting foreign keys in SQL Server?

1 Use consistent naming conventions

When working with foreign keys in SQL Server, one of the first steps is to use consistent naming conventions that follow some basic rules. For instance, you should use descriptive and meaningful names that indicate the source and target tables and columns of the foreign key, as well as prefixes or suffixes to distinguish foreign keys from other types of constraints. Additionally, it's important to consider whether the foreign key references one or many rows in the target table, such as CustomerID or OrderIDs. Furthermore, avoid using reserved words, spaces, special characters, or keywords that might conflict with SQL syntax or cause confusion. Adhering to these naming conventions will help you prevent duplication, ambiguity, and errors when creating, modifying, or querying foreign keys in SQL Server.

2 Add comments and descriptions

Adding comments and descriptions to foreign keys in SQL Server is a best practice that can help you and other database developers or users understand their role and function. To do this, you can use the sp_addextendedproperty stored procedure to add a description property to the foreign key constraint object, which will store the description in the sys.extended_properties catalog view. Additionally, you can use the -- or /* */ syntax in the CREATE TABLE or ALTER TABLE statements, which stores comments in the sys.sql_modules catalog view. Finally, you can use documentation tools or features of your preferred SQL development environment, such as SQL Doc or SQL Prompt, to generate and maintain documentation for your foreign keys and other database objects.

3 Use composite foreign keys sparingly

A composite foreign key is a foreign key referencing multiple columns in the target table, which can be useful for enforcing complex business rules or modeling many-to-many relationships. However, this type of foreign key can increase the complexity and size of the foreign key definition and the join conditions in queries, reduce the flexibility and scalability of the database design, as well as affect query performance and execution plan. As such, a best practice for naming and documenting foreign keys in SQL Server is to use composite foreign keys sparingly and only when necessary. Alternatives such as surrogate keys or junction tables should be considered to simplify and optimize your foreign key design.

4 Review and update foreign keys regularly

It is paramount to review and update foreign keys in SQL Server regularly, as your database schema and data model may change due to new or modified business requirements, data sources, or features. You can check the validity and consistency of your foreign keys using the DBCC CHECKCONSTRAINTS command. If foreign keys are no longer needed, relevant, or accurate, then you should modify or delete them using the ALTER TABLE or DROP CONSTRAINT statements, or the Delete option in SSMS. Additionally, if you need to add or modify any foreign keys to reflect new or changed relationships between tables, then use the ALTER TABLE or ADD CONSTRAINT statements, or the New Foreign Key option in SSMS. Lastly, update the names, comments, and descriptions of your foreign keys with the methods described previously. Keeping your foreign keys up-to-date will help maintain the integrity, quality, and performance of your database and ensure that your foreign keys reflect the current state and logic of your data model.

5 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?