Author: Tomas Rutkauskas 

Enumerating user tables in an InterBase database

Answer:

A list of user tables can be retrieved by querying system table rdb$relations.

The example below shows how to do this - it inserts the table names sorted 
alphabetically into a ListBox (lbSourceTables).

1   begin
2     ibcSourceList.SQL.Clear;
3     ibcSourceList.SQL.Add('select rdb$relation_name from rdb$relations');
4     ibcSourceList.SQL.Add('where rdb$system_flag = 0');
5     ibcSourceList.SQL.Add('order by rdb$relation_name');
6     ibcSourceList.Open;
7     while not ibcSourceList.Eof do
8     begin
9       lbSourceTables.Items.Add(ibcSourceList.Fields[0].AsString);
10      ibcSourceList.Next;
11    end;
12    ibcSourceList.Close;
13  end;