LOWER (Transact‑SQL)

Synopsis

LOWER ( character_expression )

Returns character_expression with all uppercase letters converted to lowercase.

Syntax

Parameter	Type	Description
`character_expression`	character, varchar, nvarchar, text, ntext	The string to convert. If `NULL`, the result is `NULL`.

Return Value

Same data type as the input expression. If the input is NULL, the result is NULL.

Examples

SELECT LOWER('SQL SERVER') AS Lowered;
-- Result: sql server

DECLARE @txt NVARCHAR(50) = N'ÄÜÖß';
SELECT LOWER(@txt) AS LoweredUnicode;
-- Result: äüöß

SELECT LOWER('SQL SERVER') AS Lowered;
SELECT LOWER(@txt) AS LoweredUnicode;

Usage Notes

Works with Unicode strings; use NVARCHAR or N prefix for proper handling.
Case‑insensitive collations may already treat values as lower case; LOWER still guarantees conversion.
Performance impact is negligible for short strings but consider set‑based operations for large volumes.

Related Functions

UPPER
LEN
REPLACE