Dynamic access to database table

Question

Hi, 
 I am working on an application that will be used for different functionalities with same environment and database, so I need to segment data depending on functionality. 
 Regrettably, data segmentation on tables is not enought for security requirements, I need to query data from different entities depending on functionality dinamically (on run time). I am trying to use a variable, of type dataStoreEntity, to set entity which query on in each case. I know that dataStoreEntity type has an ID to represents the entity, but i don't know how get it. 
 Is there any way to define the value to set on variable on run time? It's possible to get the ID of an entity, for example, by entity's name?

Mike Schmitt · Answer

Why not just build a constant for each entity, and then build an expression rule that returns the proper constant? 
 
 This is the correct answer - a constant for each DSE (which should be standard practice considering that it's basically required to create Query Entity expression rules).