Problems with mysql distinct query ... - Webmaster Forums - Webmaster forum for HTML, PHP, ASP, CSS and more

pepe_lepew1962 · 03-29-2010, 03:24 PM

Hi:

I am very new at this and totally confused as to what query I need. Here is my problem. We have bus trips all over the place and allow our drivers to put a request on routes as they become available. When the driver logs in, a session with his/her id is created. Now, display all the routes that the driver has not requested on. On the example below, when "PB" logs in and the session is created, display trips 1234, 1236, 1237 and 1238. I have a command button that is next to each trip that the driver would click and load a new screen with trip details. My problems is how to limit trips that the driver has NOT put a request on.

$D_Name = $_SESSION['sesdrivername01'];

tblTRIPS:
Trip_Num Trip_From Trip_To
1234AB Dallas Miami
1235AB Ft Worth Montreal
1236AB Houston Phoenix
1237AB Seattle Tacoma
1238AB Portland Vegas
//
//
tblDRIVER:
Driver_Load Driver
1235AB PB
1235AB AJ
1237AB PB

$frmTrip101 = "SELECT DISTINCT Trip_Num,Trip_From,Trip_To,Driver_Load FROM tblTRIPS, tblDRIVER where tblTRIPS.Trip_Num != tblDRIVER.Driver_Load";

php_mysql_coder · 04-15-2010, 06:28 AM

distinct is not a good way to do what you want. with distinct you just pick out the elements which are different. this is just for avoiding from repetitions.

a simple way to do what you want is building new column and assigning true and false according to the reservations. so you can pick out true ones as reserved ones and false ones as non-reserved ones.

tell me if you need further help or correct me if I missunderstood..

thanks.