Two variables that are dependent on each other

I have two variables and they actually contain the same thing. Now if I change query0 I want the value in query1 to be selected. Conversely, if I change query1, I want the value in query0 to be selected.

Thought I’d do that in SQL via
Select as 'Line', org_l1.id_kunde as Workcenter From org_l1 WHERE org_l1.id_kunde = ~ /$query1$/

Select org_l1.id_kunde as Workcenter, as Line From org_l1 WHERE = ~ /$query0$/

Unfortunately that doesn’t work. Anyone have an idea?