SQL Server Best Practices: [dbo] vs. dbo – A Guide to Consistency

When browsing through SQL scripts, you’ve likely seen schema-qualified table names written in two distinct ways: dbo.MyTable and [dbo].[MyTable]. Functionally, they often seem to produce the same result, which begs the question: Does it matter which one you use? And if so, which one is better?

Consistency in a codebase is a hallmark of quality. While the database engine might not care which syntax you use, your team members (and your future self) certainly will. Let’s dive into the difference between these two forms and establish a clear, simple best practice.

The Key Difference: Regular vs. Delimited Identifiers

The distinction between dbo and [dbo] boils down to how SQL Server interprets object names. These are known as “identifiers.”

1. dbo (Regular Identifier)

A regular identifier is a standard, unquoted object name. It must follow a specific set of rules:

• It cannot be a SQL Server reserved keyword (like SELECT, TABLE, ORDER).
• It cannot contain spaces or special characters (other than a few exceptions like the underscore _).
• It must start with a letter or an underscore.

The name dbo fits these rules perfectly. It’s not a reserved word and contains no special characters, so it can be used directly.

2. [dbo] (Delimited Identifier)

A delimited identifier is an object name enclosed in double quotes (") or, more commonly in SQL Server, square brackets ([]). Delimiters serve a crucial purpose: they tell the SQL parser to treat everything inside them as a single name, regardless of whether it violates the rules for regular identifiers.

This is why they exist—to allow for object names that are otherwise illegal. For example:

• Reserved Keywords: If you need to create a table named Order (a reserved keyword for the ORDER BY clause), you must delimit it:

CREATE TABLE [Order] (
   OrderID INT PRIMARY KEY,
   OrderDate DATETIME
);

• Spaces or Special Characters: If your table name includes a space, it must be delimited:

SELECT * FROM [Order Details];

In the case of [dbo], the square brackets are syntactically valid but functionally unnecessary, because dbo is already a perfectly valid regular identifier.

The Recommendation: Standardize on dbo

For the sake of clarity, consistency, and readability, the recommended best practice is clear:

Use dbo (without brackets) in all cases. Only use square brackets [] for identifiers that absolutely require them.

Why Is This the Better Practice?

1. Readability and Conciseness: dbo.Users is cleaner and easier to read than [dbo].[Users]. Less visual clutter allows developers to focus on the logic of the query, not the syntax.
2. Clarity of Intent: Adopting a “delimit only when necessary” rule creates a powerful convention. When a developer sees square brackets around a name, it immediately signals that the name is special—it’s likely a reserved keyword or contains non-standard characters. If you bracket everything, this important signal is lost.
3. Consistency: Choosing one standard and sticking to it eliminates pointless variations in your codebase. This makes the code more predictable and easier to maintain.

A Simple Style Guide for Your Team

Here’s a two-part rule you can add to your team’s SQL style guide:

• Rule 1: Always refer to the dbo schema without brackets.
• Do: SELECT FirstName, LastName FROM dbo.Employees;
• Don’t: SELECT FirstName, LastName FROM [dbo].[Employees];
• Rule 2: Use square brackets [] only when an identifier is a reserved keyword or contains spaces/special characters.
• Do: SELECT * FROM dbo.[Order Details];
• Do: SELECT * FROM dbo.[User];
• Don’t: SELECT * FROM [dbo].[Products]; (when Products doesn’t require brackets)

How to Enforce This Standard

• Documentation: Add this guideline to your team’s official coding standards documentation.
• Code Reviews: Make it a quick check during pull requests. A gentle reminder is often all that’s needed to build the habit.
• Automated Tools: For larger teams, consider using SQL formatting tools like SQL Pretty Printer or linters like SQLFluff. These tools can be configured to automatically enforce identifier styling, saving everyone time and effort.

Conclusion

While SQL Server will happily accept both dbo and [dbo], the choice you make impacts your code’s quality and maintainability. By standardizing on the cleaner, non-delimited dbo form, you create a more readable and consistent codebase where the use of delimiters correctly signals an exceptional name. It’s a small detail that reflects a professional approach to writing SQL.