Just install the SQL query, and then fill in the parameters. Use parameter names that make sense to you, of course; I just used LastName and FirstName for an example. I updated to use TADOQuery instead of just TQuery after editing the question.
ADOQuery1.SQL.Clear; ADOQuery1.SQL.Add('SELECT * FROM MyTable'); ADOQuery1.SQL.Add('WHERE LastName = :LastName AND'); ADOQuery1.SQL.Add('FirstName = :FirstName'); // Populate the parameters and open it ADOQuery1.Parameters.ParamByName('LastName').Value := 'Jones'; ADOQuery1.Parameters.ParamByName('FirstName').Value := 'James'; ADOQuery1.Open; // Use query results ADOQuery1.Close; // Populate parameters with new values and open again // Populate the parameters and open it ADOQuery1.Parameters.ParamByName('LastName').Value := 'Smith'; ADOQuery1.Parameters.ParamByName('FirstName').Value := 'Sam'; ADOQuery1.Open; // Use new query results ADOQuery1.Close;