SQL to retrieve values on current expense entry

Hi All,

I was wondering if someone can help me with an SQL query or even just to confirm whether it's possible at all? We currently have a requirement to limit some of the available values in the expense dff based on previous selections on the same expense. In effect, when the user selects the Entity Segment, we need to use it as a binding parameter in our WHERE clause for the dff. So to start with, if someone could even tell me what the SQL query should be to retrieve the Entity Segment on the current expense entry, would be extremely