Hello

Environment Delphi 11.2

Latest dbexpress drivers for Oracle and PostgreSQL

PostgreSQL database:

Insert sqlconnection, configure access, connected := Truee

Insert SQLQuery, link to connection, edit SQL:  "select * from TABLE where field = :P1" Confirm

Do nothing to specify parameter P1 so that stay unknown

Add Datasetprovider, link to SQLQuery

Add ClientDataSet, link to Datasetprovider

Set ClientDataset Active to True: It will go active

With Oracle, do exactly the same; direct connection or not is not relevant

When you activate ClientDataset1 you obtain "catastrofic failure"