PostgreSQL - LOWER function

The LOWER() function in PostgreSQL converts all uppercase letters in a string to lowercase based on the database's locale rules.

• Convert text to lowercase.
• Standardize string values.
• Perform case-insensitive searches.
• Format text consistently.

Syntax

LOWER(string)

Where:

• string: The text or column value to convert to lowercase. It can be of type CHAR, VARCHAR or TEXT.

Working

Consider the following Books table for the examples below:

Example 1: Convert a String to Lowercase

The following query converts the string 'PostgreSQL' to lowercase.

Query:

SELECT LOWER('PostgreSQL') AS LowerText;

Output:

• The LOWER() function converts all uppercase letters in the string to lowercase.

Example 2: Convert Book Titles to Lowercase

The following query converts the book titles to lowercase.

Query:

SELECT
    LOWER(BookTitle) AS LowerBookTitle
FROM
    Books
ORDER BY
    BookTitle;

Output:

• The LOWER() function converts all characters in the BookTitle column to lowercase.

Example 3: Using LOWER() in the WHERE Clause

The following query retrieves books in the Programming category by comparing the lowercase value.

Query:

SELECT
    BookTitle,
    Category
FROM
    Books
WHERE
    LOWER(Category) = 'programming';

Output:

• The LOWER() function converts the Category value to lowercase before comparison, allowing a case-insensitive search.