the key to dynamic dropdowns, whether using 1 table, 2 tables or more is creating your recordsets correctly.
the recordsets are where you create the parent child relationships.
The Create Dynamic Array behavior takes three pieces of data from your recordset:
Parent ID
Child ID
Child Name
The Parent ID is the column that is used to create the Parent to Child relationship. It will be used to compare the value coming from the parent select list.
The Child ID is the column that will be used for the value of the child list.
The Child Name will be used for the Label of the child select list.