JavaScript and MySQL

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  • Jens Körte
    #1

    JavaScript and MySQL

    Hi!

    I've got a typical newbie-problem, I guess.
    I got some selectboxes on my site. these boxes get their data from a
    databse. everything works fine, but when a user selects a value from
    one of the boxes i want to change the values from the other boxes
    dynamically. The values are derived from the database. Initially the
    boxes get for example those inputs:
    Box1 --> SELECT * FROM VEHICLE
    Box2 --> SELECT * FROM CAR

    If a user selects "car" from Box1, Box2 must change his content so
    that only cars are shown, i.e. no trucks, no bicylces, etc...
    Something like that:
    SELECT c.name FROM CAR c WHERE VEHICLE = 'car'

    With the onChange-event I can handle the values. No problem with that.
    But how do I get the data from the database into the
    javascript-statement. How do I have to handle this. I have no idea.
    Please help...


    Jens

    P.S. I only want to use PHP, HTML and Javascript.
    Tags: None
    • Joakim Braun
      #2
      Re: JavaScript and MySQL

      "Jens Körte" <jk060674@gmx.d e> skrev i meddelandet
      news:ckprn0ppml gudmppbq1biugbo a4gbh9a1h@4ax.c om...[color=blue]
      > Hi!
      >
      > I've got a typical newbie-problem, I guess.
      > I got some selectboxes on my site. these boxes get their data from a
      > databse. everything works fine, but when a user selects a value from
      > one of the boxes i want to change the values from the other boxes
      > dynamically. The values are derived from the database. Initially the
      > boxes get for example those inputs:
      > Box1 --> SELECT * FROM VEHICLE
      > Box2 --> SELECT * FROM CAR
      >
      > If a user selects "car" from Box1, Box2 must change his content so
      > that only cars are shown, i.e. no trucks, no bicylces, etc...
      > Something like that:
      > SELECT c.name FROM CAR c WHERE VEHICLE = 'car'
      >
      > With the onChange-event I can handle the values. No problem with that.
      > But how do I get the data from the database into the
      > javascript-statement. How do I have to handle this. I have no idea.
      > Please help...
      >
      >
      > Jens[/color]

      Unless you want to do a reload whenever Box1 changes (and write the
      <options> directly server-side), you can write a dynamic Javascript with,
      for instance, PHP. Something like this (PHP pseudo-code, but you get the
      idea):

      function writeDynamicJav ascript(){

      $result = 'function box1changed(inN ewValue){' . "\n";
      $box1Values = /* get possible values from MySQL as PHP array */;

      $result .= 'var box2Values = new Array();' . "\n";
      $result .= 'var ctr = 0;' . "\n";
      $result .= 'switch(inNewVa lue){' . "\n"

      foreach($box1Va lues as $box1Value){
      $result .= 'case "' . $box1Value . '":' . "\n";
      /* fill the JS theResult variable of the dynamic JS function with
      values box2 can take */
      /* if box 1:s value is $box1Value - a loop something like:
      $result .= 'box2Values[ctr++] = "' . /* some value */ . '";' . "\n";
      $result .= 'break;' . "\n";

      }

      $result .= '}' . "\n"; // close JS switch

      /* Add JS code here to reload box2 from the array elements now in
      box2Values */

      $result .= '}' . "\n"; // close JS function
      return $result;
      }

      You echo the result of writeDynamicJav ascript() into the <head> of the
      document. Then you add onchange="box1c hanged(this.val ue);" (the name of the
      JS function that writeDynamicJav ascript() generates) to box 1.

      Note that if either of the <select> boxes can take a lot of values, this may
      result in an arbitrarily large Javascript in the <head>... But for a limited
      number of choices, it works well.

      Joakim Braun


        Comment

        • Joakim Braun
          #3
          Re: JavaScript and MySQL


          "Joakim Braun" <joakim.braun@j fbraun.removeth is.com> skrev i meddelandet
          news:8Pofd.8992 $1p.7706@nntpse rver.swip.net.. .[color=blue]
          > Unless you want to do a reload whenever Box1 changes[/color]

          <snip>

          What I meant was: Unless you want to post the form and regenerate the
          document whenever Box1 changes...

          Joakim Braun


            Comment

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