query1.Close; query1.SQL.Clear; query1.SQL.Add('select * from x where last_name=:last_name'); //引号中没有; query1.ParamByName('last_name').AsString:='Davis'; query1.Open;
query1.SQL.Add('select * from x where last_name='':last_name'''); query1.ParamByName('last_name').AsString:='Davis';
query1.ParamByName('').AsString:='Davis';
query1.ParamByName('last_name').AsString:='Davis';
query1.SQL.Clear;
query1.SQL.Add('select * from x where last_name=:last_name'); //引号中没有;
query1.ParamByName('last_name').AsString:='Davis';
query1.Open;
query1.ParamByName('last_name').AsString:='Davis';