Case sensitivity is controlled by the character setting you used for the field in the database itself. Go to the table and column and check the collation value for that column. You can then do a google search to find which collate values are case sensitive and not to set them appropriately for your application.
There are ways to do this in the SQL statement if you want some searches to be case sensitive and others not by updating the collate value on the fly, but I've always done it in the database itself.