Db2 LOWER

Summary: in this tutorial, you will learn how to use the Db2 LOWER() function to transform all characters of a string to lowercase.

DB2 LOWER() function overview #

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

The following shows the syntax of the LOWER() function:

LOWER(expression)
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In this syntax, the expression is a character string expression that evaluates to a string or a value which can be implicitly converted to a string.

Similar to the UPPER() function, the LOWER() function can be useful for case insensitive searches.

Db2 LOWER() function examples #

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

1) Using Db2 LOWER() to convert a literal string to lowercase #

The following example uses the LOWER() function to convert the string 'Db2 lower' to uppercase:

SELECT
    LOWER('Db2 lower') result
FROM
    sysibm.sysdummy1;
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Here is the result set:

RESULT    
--------- 
db2 lower 
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2) Using Db2 LOWER() to perform case insensitive searches #

See the following publishers table in the sample database:

This example uses the LOWER() function to find the publisher whose name is apress:

SELECT
    publisher_id,
    name 
FROM publishers
WHERE 
    LOWER(name) = 'apress';
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Here is the output:

PUBLISHER_ID NAME                                                                    
------------ ------- 
14           Apress 
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To improve the speed of the query, you can create an expression-based index on the name column of the publishers table:

CREATE INDEX ix_uname
ON publishers(UPPER(name));
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In this tutorial, you have learned how to use the Db2 LOWER() function to convert all characters of a string to lowercase.

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