First off, are you running EG 4.1 or EG 4.2? EG 4.2 has some nice additions to date prompts, including support for intervals like month and year.
If you're using EG 4.2, try the following:
1. Select View / Prompt Manager.
2. Click Add to begin creating a new prompt. After picking a name etc., go to the second tab. Make it a date prompt, user enters values, date type of Month.
When the prompt gets used, it will create serveral macro variables behind the scenes. Let's say, for example, you called your prompt MP_new. After supplying a prompt value like January 2003, the code behind the scenes would have the following macro variable values available:
1. MP_new_label = January 2003
2. MP_new= 01Jan2003
3. MP_new_end = 31Jan2003
Using a filter in the query builder, you could then create an advanced filter. If you column was date_column_1 then:
date_column_1 between "&MP_new"d and "MP_new_end"d
Sadly, I don't see a point-and-click way to easily create this filter... but at least the month prompt interface makes choosing a value easier. Someone else on the forum might have a slicker solution for the filter part.