In MySQL, the LOWER() function converts uppercase characters to lowercase, according to the current character set mapping (the default mapping is utf8mb4).

Syntax

The syntax goes like this:

LOWER(str)

Where str is the string to be changed to lowercase.

Example

Here’s an example:

SELECT LOWER('CAT');

Result:

+--------------+
| LOWER('CAT') |
+--------------+
| cat          |
+--------------+

Of course, if the string already contains any lowercase characters, those characters will remain lowercase.

Example:

SELECT LOWER('Cat');

Result:

+--------------+
| LOWER('Cat') |
+--------------+
| cat          |
+--------------+

Database Example

Here’s an example of selecting data from a database and converting it to lowercase:

USE Music;
SELECT 
    ArtistName AS Original, 
    LOWER(ArtistName) AS Lowercase
FROM Artists
LIMIT 5;

Result:

+------------------+------------------+
| Original         | Lowercase        |
+------------------+------------------+
| Iron Maiden      | iron maiden      |
| AC/DC            | ac/dc            |
| Allan Holdsworth | allan holdsworth |
| Buddy Rich       | buddy rich       |
| Devin Townsend   | devin townsend   |
+------------------+------------------+

Binary Strings

This function doesn’t work on binary strings. If you need to use it on a binary string, you’ll need to convert it to a nonbinary string first. Here’s an example:

SET @str = BINARY 'Cat';
SELECT 
  LOWER(@str) AS 'Binary', 
  LOWER(CONVERT(@str USING utf8mb4)) AS 'Nonbinary';

Result:

+--------+-----------+
| Binary | Nonbinary |
+--------+-----------+
| Cat    | cat       |
+--------+-----------+

The LCASE() Function

The LCASE() function is a synonym for LOWER(). Note that if you use LCASE() within a view, it will be rewritten and stored as LOWER().

Convert to Uppercase

The UPPER() and UCASE() functions work the same way to convert characters to uppercase.