SQL Server LOWER() Function

In SQL Server, the LOWER() function is used to convert a string to lowercase. This function is very simple and easy to use, and is very useful in scenarios where a string needs to be converted to lowercase.

Syntax

LOWER(string)

Here, string is the string to be converted to lowercase.

Use Cases

Here are some use cases for the LOWER() function:

• Strings stored in a database may appear in different forms, such as some user input strings may contain uppercase letters while some are all lowercase. Using the LOWER() function can convert these strings to a uniform lowercase form for easier processing and comparison.
• When comparing strings, using the LOWER() function can convert strings to the same case to avoid errors caused by case sensitivity.

Examples

Here are two examples of using the LOWER() function:

Example 1

Suppose we have a table named products with a product_name field that stores product names. Since user-entered product names may vary in case, we need to convert all product names to lowercase for easy comparison and processing.

Here is an SQL query using the LOWER() function:

SELECT LOWER(product_name) FROM products;

Running this query will return the lowercase form of all product names.

Example 2

Suppose we have a table named users with an email field that stores user email addresses. Now we need to query all user information with the email address example.com.

Since the case of letters in email addresses may differ, we need to first convert the value of the email field to lowercase and then compare it to example.com.

Here is an SQL query using the LOWER() function:

SELECT * FROM users WHERE LOWER(email) = 'example.com';

Running this query will return all user information with the email address example.com.

Conclusion

The LOWER() function can convert a string to lowercase, making it easier for processing and comparison. Using the LOWER() function in scenarios where strings need to be converted to the same case can reduce the possibility of errors.