Understanding CONCAT in SQL Server

Welcome Dev! In this article, we will discuss the CONCAT function in SQL Server. If you’re a beginner or an experienced developer looking for a refresher, this article is for you. Let’s dive into the world of SQL Server together!

What is CONCAT?

The CONCAT function in SQL Server is used to concatenate two or more strings into one string. It is available in SQL Server 2012 and later versions. CONCAT is a built-in function that can be used to concatenate different types of data such as text, numbers, and dates.

Let’s see how the CONCAT function works:

Expression
Result
SELECT CONCAT(‘Hello’, ‘World’)
HelloWorld
SELECT CONCAT(‘Hello’, ‘ ‘, ‘World’)
Hello World
SELECT CONCAT(100,20)
10020

Using CONCAT in SQL Queries

The CONCAT function can be used in SQL queries to concatenate columns or values from different columns. Let’s take a look at some examples:

Example 1: Concatenate two columns:

First Name
Last Name
Full Name
John
Doe
SELECT CONCAT(First_Name, ‘ ‘, Last_Name) AS ‘Full Name’ FROM Customers

Example 2: Concatenate a column with a string:

Product Name
Price
Price with Currency
Product A
$50
SELECT CONCAT(‘$’, Price) AS ‘Price with Currency’ FROM Products

FAQs

What is the difference between CONCAT and CONCAT_WS?

The CONCAT_WS function is similar to CONCAT, but it allows you to specify a separator between the concatenated values. For example, if you want to concatenate two columns with a hyphen separator, you can use CONCAT_WS as follows:

SELECT CONCAT_WS(‘-‘, Column1, Column2) AS ‘Concatenated Value’ FROM Table

What is the maximum length of the concatenated value?

The maximum length of the concatenated value depends on the data type of the resulting expression. For example, if the resulting expression is a varchar, the maximum length is 8,000 characters. If the resulting expression is a nvarchar, the maximum length is 4,000 characters.

Can I use CONCAT to concatenate NULL values?

If any of the values passed as arguments to CONCAT are NULL, the resulting value will be NULL. To concatenate values that may contain NULL values, you can use the ISNULL or COALESCE function.

Can I use CONCAT in a WHERE clause?

Yes, you can use CONCAT in a WHERE clause to filter rows based on concatenated values. For example:

SELECT * FROM Table WHERE CONCAT(Column1, Column2) = ‘Value’

Is there any performance difference between using CONCAT and + to concatenate strings?

There is no significant performance difference between using CONCAT and + to concatenate strings. However, CONCAT is recommended because it is more flexible and can concatenate different types of data.

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Conclusion

That’s it, Dev! We hope this article has provided you with a clear understanding of the CONCAT function in SQL Server. Whether you’re a beginner or an experienced developer, this function can be a powerful tool in your SQL toolkit. Remember to use CONCAT whenever you need to concatenate strings or values in your SQL queries.

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