如何在php中验证循环值？ 第1栏>第2栏

Question

enter image description here

The above image due value 19948 and the input value are not greater than the due value 19948. How to validate this in javascript or jquery or php?

<?php
$i = 0;
$sql = "select * from invoice where `cid`='5'";
$res = mysql_query($sql);
$numrows = mysql_num_rows($res);
while ($row = mysql_fetch_array($res)) {

        $i = $i + 1;

        echo "<tr>";

        echo "<td>" . $row['customername'] . "</td>";
        echo "<td>" . $row['totalamount'] . "</td>";
        echo "<td>" . $row['paidamount'] . "</td>";
        echo "<td>" . $row['dueamount'] . "</td>";

        ?>


        <?php

        echo "<td><input type='text' name='ichange$i' value='0'  onkeyup='ivalue()'  />
                      <input type='hidden' name='idue$i' value='$due'   /></td>";
        echo "</td>"; 

        echo "</tr>";

}

 echo "<input type='hidden' name='nrows' value='$numrows' />";

?>

 <script>

     function ivalue()
    {

        nrows=document.getElementsByName("nrows").item(0).value;

        for(i=1;i<=nrows;i++)
        {
            ichange="ichange" + i;
            idue="idue" + i;

            if(document.getElementsByName(ichange).item(0).value>document.getElementsByName(idue).item(0).value)    
            {
               alert("Value not greater than due value")

            }


        }


    } 

</script>

Answer 1

I suppose you want to alert the user if he enters a greater value than the due in the same row. I would use jQuery here since you tagged it :

$('input[type="text"]').on('keyup',function(){
    if($(this).val() > $(this).next().val()){
        alert("Value not greater than due value")
    }
})

You could add some classes to your html for an easier and more precise select.