Db2 UPPER() Function: Convert a String to Uppercase

Summary: in this tutorial, you will learn how to use the Db2 UPPER() function to convert all characters of a string to uppercase.

DB2 `UPPER()` function overview

The UPPER() function accepts a string and returns a new string in which all characters in the original string are converted to uppercase.

Here is the syntax of the UPPER() function

UPPER(expression)

In this syntax, the expression must evaluate to a character string or a value that can be implicitly converted to a character string.

The UPPER() function is useful for case-insensitive searches.

Let’s take some examples of using the UPPER() function.

This example uses the UPPER() function to convert the string 'Db2 upper' to uppercase:

SELECT
    UPPER('Db2 upper') result
FROM
    sysibm.sysdummy1;

Here is the result set:

RESULT    
--------- 
DB2 UPPER

See the following authors table from the sample database:

The following example uses the UPPER() function to search for authors whose last name are Anderson:

SELECT
    author_id,
    first_name,
    last_name
FROM
    authors
WHERE 
    UPPER(last_name) = 'ANDERSON';

Here is the output:

To speed up this query, you should consider creating an expression-based index for the last_name column:

CREATE INDEX ix_ulastname
ON authors(UPPER(last_name));

In this tutorial, you have learned how to use the Db2 UPPER() function to convert all characters of a string to uppercase.