CONCAT()

The CONCAT() function in SQL is used to join two or more strings into a single string.

It is widely used for combining columns, literals, or expressions into meaningful data, such as full names or formatted outputs.

Syntax

CONCAT(string1, string2, ..., stringN)

• string1, string2, ..., stringN: The strings or expressions to concatenate. These can be columns, string literals, or other expressions. A minimum of two strings must be provided.

Note: If any argument is NULL, the result will also be NULL.

Example

Suppose there is a table employees with the following data:

To create a column with full names, the following query including CONCAT() can be used:

SELECT CONCAT(first_name, ' ', last_name) AS full_name
FROM employees;

The output of the above example will be as follows:

| full_name       |
|------------------|
| John Doe         |
| Alice Smith      |
| Mark Johnson     |

Let’s say that there’s a need to create email addresses from the first_name and last_name. In this case, the CONCAT() function can combine these columns with a domain name as follows:

SELECT CONCAT(LOWER(first_name), '.', LOWER(last_name), '@company.com') AS email
FROM employees;

The output of the above example will be as follows:

| email                 |
|-----------------------|
| [email protected]  |
| [email protected]|
| [email protected]|