asked on

Validate textbox value

HI ALL,

I have a textbox nd a submit button on my .aspx page.

Is there a way i can validate if the value entered in the textbox exist in a table? I would like to do this before the user clicks on the submit button.

Thanks!!

nathana21

add some code to your page...with the event onChange on the text box..make the code run a function on the page that:

opens the database
runs the following sql

select * from <Table> where <form field> = <table>.field
if record set is empty..
do something.

close recordset
close db

rlbalan

Good fit for an AJAX call.
onChange invoke an AJAX function to return true/ false from your DB. Then alert the user if it fails.
PS : The response will be as fast as your DB query here.. SO it better be a simple lookup in DB

dakyd

Why not make it a drop down (<select>) instead? You would populate that drop down with the existing values in your table. That way, the validation is inherently done for you, since it's now impossible to enter a value that doesn't exist in the db.

siva_siva

I have done this one php you change this in ASP.NET

<?php
      include('connectdb.php');

      // After enter the value in the textbox called through Ajax
      if(isset($_REQUEST['value'])) {
            $value = $_REQUEST['value'];
            if($value != '') {
                  $valuequery = "SELECT * FROM users where UserName = '$value'";
                  $valueresult = mysql_query($valuequery);
                  $valuerow = mysql_num_rows($valueresult);

                  // display the correct value for the value
                  if($valuerow > 0) {
                        echo "<input type=text name=test value='' onchange='check_database();'>";
                        echo "<br><font color=red><b>Value is in database</b></font>";
                  }
                  else {
                        echo "<input type=text name=test value='$value' onchange='check_database();'>";
                        echo "<br><font color=green><b>Value is not in database</b></font>";
                  }
            }
            exit;
      }
?>
<html>
<title>Validate</title>
<head>
      
      <script src="scripts/prototype.js" type="text/javascript"></script>
      <script>
            function checkform() {
                  with(document.validateform){
                        if(test.value == '') {
                              alert('Please enter some value');
                              test.focus();
                              return false;
                        }
                  }
                  return false;
            }

            function check_database() {
                  // In which the textbox is display ("id value for the td textbox")
                  var target = 'textvalue';
                  var url = 'validate.php';
                  var params = 'value='+document.validateform.test.value;
                  new Ajax.Updater(target,url,{ parameters:params });
            }
      </script>
</head>
<body>
<form name="validateform" action="validate.php" method="post">
      <table>
            <tr>
                  <td id="textvalue"><input type="text" name="test" value="" onchange="check_database();"></td>
            </tr>
            <tr>
                  <td><input type="button" name="submit" value="Submit" onclick="return checkform();"></td>
            </tr>
      </table>
</form>
</body>
</html>

ASKER CERTIFIED SOLUTION

joan2006

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

Vee_Mod

Closed, 500 points refunded.
Vee_Mod
Community Support Moderator