In PostgreSQL, we can use the upper() function to convert lowercase characters to their uppercase equivalent, according to the rules of the database’s locale.

Syntax

The syntax goes like this:

upper ( text )

Where text is the text to be converted to uppercase.

Example

SELECT upper('Louder!');

Result:

LOUDER!

Any uppercase characters remain uppercase, while lowercase characters are converted to uppercase.

Database Example

Here’s an example of converting the results of a database query to uppercase:

SELECT 
    firstname,
    UPPER(firstname)
FROM Dogs;

Result:

+-----------+-------+
| firstname | upper |
+-----------+-------+
| Bark      | BARK  |
| Woof      | WOOF  |
| Ruff      | RUFF  |
| Wag       | WAG   |
+-----------+-------+

Here I converted the firstname column to its uppercase equivalent.

To convert the other way around (from uppercase to lowercase), we can use lower().