Understanding “set nocount” in SQL Server

Hey Dev, are you familiar with the “set nocount” statement in SQL Server? If not, don’t worry! In this article, we’ll dive deep into this statement and explain how it works, its benefits, and how you can use it in your SQL Server queries.

What is “set nocount” in SQL Server?

When you execute a query in SQL Server, by default, the server returns a message indicating the number of rows affected by that query. This message is called the “row count” message. For some queries, this message may not be useful, and it can slow down the query performance.

Here is where the “set nocount” statement comes into play. When you use this statement, SQL Server will not return the row count message, improving the query performance and reducing network traffic.

How does “set nocount” work?

The “set nocount” statement is a T-SQL command that tells SQL Server not to return the row count message for any statement that follows it. This statement affects the entire session and all subsequent queries, unless you explicitly turn it off by using “set count on”.

Let’s take a look at an example:

SET NOCOUNT ONSELECT * FROM CustomersSELECT * FROM Orders

-- No row count message returned-- Rows from Customers table-- Rows from Orders table

SET NOCOUNT OFFSELECT * FROM CustomersSELECT * FROM Orders

-- Row count message returned-- Rows from Customers table-- Rows from Orders table

Benefits of using “set nocount”

Now that you know how “set nocount” works, let’s take a look at some of its benefits:

Improved query performance

Returning the row count message for each statement can slow down the query performance, especially for large tables or complex queries. By using “set nocount”, you can eliminate this overhead and improve the query response time.

Reduced network traffic

When SQL Server returns the row count message, it adds overhead to the network traffic, especially when you’re working with remote servers or slow network connections. By using “set nocount”, you can reduce the amount of data that needs to be transferred over the network.

Cleaner output

In some scenarios, the row count message can clutter the query output, making it harder to read and analyze. By using “set nocount”, you can make the query output cleaner and more readable.

FAQ about “set nocount”

Can I use “set nocount” with stored procedures?

Yes, you can use “set nocount” with stored procedures. In fact, it’s a best practice to use this statement in all your stored procedures to improve their performance and reduce network traffic.

Does “set nocount” affect the @@ROWCOUNT variable?

No, “set nocount” does not affect the @@ROWCOUNT variable. This variable still returns the number of rows affected by the last statement executed.

Do I need to use “set nocount” in all my queries?

No, you don’t need to use “set nocount” in all your queries. You should use it only for queries where the row count message is not useful and can slow down the performance.

Can “set nocount” affect the behavior of triggers?

Yes, “set nocount” can affect the behavior of triggers. If you use “set nocount” in a trigger, SQL Server will not return the row count message for any statement executed within that trigger.

Conclusion

By using “set nocount” in your SQL Server queries, you can improve their performance, reduce network traffic, and make the query output cleaner and more readable. It’s a best practice to use this statement in all your stored procedures and queries where the row count message is not useful. We hope this article has helped you understand how “set nocount” works and how you can benefit from using it in your SQL Server queries. If you have any questions or feedback, please leave a comment below. Happy coding!