If returning data in associative mode, it is important to choose early in the project whether to use upper case or lower case keys. Once that decision has been made, a consistent result can be expected. ADOdb controls the casing of the keys using the ADODB_ASSOC_CASE constant. 
The constant must be defined before the inclusion of the ADOdb libraries
There are 3 possible values: ADODB_ASSOC_CASE_LOWER, ADODB_ASSOC_CASE_UPPER and ADODB_ASSOC_CASE_NATIVE (Default). Note that use of native case is not recommended when writing portable applications.
See ADODB_ASSOC_CASE in the reference manual for further information and usage examples.