Drop down lists select all query

This is probably an easy one for you experts out there. I searched the forum and found similar things but I couldnt get them to work.

I have a drop down list tied to a row in a table.
This drop down list is then tied to a where claus on a table so the user can choose their query.
As the table row does not have a choose ALL I added a button the user can press to choose all. This button sends a value of “” to the drop down list selected string value.
This query works as when the user presses the select all button the table shows all the projects and sites as it finds all the records that are not empty.
But when the user selects from the list it shows everything but the selected option as its not =

Whats the best way around this ?

FROM Project
WHERE SITE >’{Root Container.Dropdown.selectedStringValue}’

I usually do this with a custom property that holds the entire WHERE clause.

The Custom Property will have something like:

if ({Root Container.Dropdown.selectedValue}=0, "", concat("WHERE SITE = '",{Root Container.Dropdown.selectedStringValue},"'") )

The query would then change to:

SELECT * FROM Project '{Root Container.Dropdown.Where_Clause}'