How to get only Messages where some specific custom field have value?

Hi Team,

I have a custom field added by Khoros in the messages object, I want to get only Messages where that specific custom field has value.

Sample query:
select c_abcd from messages where c_abcd!=""

I don't want to get all messages and then in the loop filter the messages which don't have any value.

Is there any direct API or solution to get the messages where the c_abcd custom field has some value?

Any related replies would be appreciated.

Regards
Aman