Php undefine variable issue - php

Question

I've a html form which is insert data to mysql database and then get those data with following php code (From supplier_jv table)
<?php
include("include/address2.php");
include("include/menu.php");
$uname_ad = $_SESSION['uname_ad'];
$id = $_GET['id'];
$sql = mysql_query("SELECT * FROM supplier_jv WHERE jv_id = '$id'");
$num = mysql_num_rows($sql);
if($num == 0)
{
echo "<p><font color=red>Accounts is emtpy</font></p>";
}
else
{
$re_name = mysql_fetch_array($sql);
echo "<center><h2>";
echo "<strong>Accounts of </strong>";
echo $re_name['jv_name'];
echo "</h2></center>";
echo "<center>";
echo "<table>";
echo "<table border='0' cellpadding='5' cellspacing='5' width='1000'>";
echo "<tr/>";
echo "<td><strong>Date</strong></td>";
echo "<td><strong>Particular</strong></td>";
echo "<td><strong>Folio(C)</strong></td>";
echo "<td><strong>Folio(J)</strong></td>";
echo "<td><strong>Debit</strong></td>";
echo "<td><strong>Credit</strong></td>";
echo "<td><strong>Balance</strong></td>";
echo "</tr>";
while($re= mysql_fetch_array($sql))
{
$day = $re['day'];
$month $re['month'];
$year = $re['year'];
$parti = $re['particulars'];
$folio = $re['folio'];
$folio2 = $re['folio2'];
$debit = $re['debit'];
$credit = $re['credit'];
$balance = $re['balance'];
$b = $debit - $credit;
$total_debit = mysql_query("SELECT SUM(debit) FROM supplier_jv");
$re_t = mysql_fetch_array($total_debit);
$t_d = $re_t['SUM(debit)'];
$total_credit = mysql_query("SELECT SUM(credit) FROM supplier_jv");
$re_t2 = mysql_fetch_array($total_credit);
$t_c = $re_t2['SUM(credit)'];
$b = $t_d - $t_c;
echo "<tr>";
echo "<td>$day/$month/$year</td>";
echo "<td>$parti</td>";
echo "<td>$folio</td>";
echo "<td>$folio2</td>";
echo "<td>";
echo number_format($debit);
echo "</td>";
echo "<td>";
echo number_format($credit);
echo "</td>";
echo "<td></td>";
echo "</tr>";
}
echo "<tr bgcolor='#f3f3f3'>";
echo "<td></td>";
echo "<td></td>";
echo "<td></td>";
echo "<td></td>";
echo "<td></td>";
echo "<td><strong>Total Balance-</strong></td>;
echo "<td><strong>";
echo number_format($b);
echo "</strong></td>";
echo "</tr>";
echo "</table>";
echo "</center>";
}
?>
Well, After insert data then it's show:
Notice: Undefined variable: b in E:\xampp\htdocs\Accounts\admin\content
\supplier_account.php on line 108
But if i insert data in second time then it's OK!!.
Any idea or solution.
Thanks
shibbir.

Answer 1

You need to use isset to see if it is set, not null and also avoid the Notice: Undefined variable error:
if (isset($b))
{
// your code here
}
Where you have:
$b = $t_d - $t_c;
Make sure that there is some value coming up for $t_d and $t_c