Showing dependencies with a data flow diagram?
If you are asking can you show dependencies in a data flow
diagram; the answer would be yes.
Under traditional guidelines however you would use a UML diagram
for this purpose. A UML Diagram will be used to show detailed
database architecture. A data Flow diagram will show the FLOW
representation of data; from the application, through the middle
tier, and database. This is used as the name represents to
demonstrate the FLOW from point A to point Z. UML will show the
actual structure of your database; the tables, fields in the
tables, relationships, etc. this will typically be accompanied by
full database documentation which will detail the intended use of
the database, external system dependencies.