how to define variables as numeric

[guitarzRus]

Hi, I have some issues with my code. It's to refresh account payfile at end of month. Comments are noted
in code (//).
#1) how to define variables as numeric(I've tried several examples(forums and manuals)
#2) how to add several variables together so they are known as numeric(they are all decimal 8,2 in the database)
#3) Please, someone explain the "Undefined variable: mysql".

[/b]

Code: [Select]

<?php
//Open a new connection to the MySQL server
$link = mysqli_connect("localhost", "root", "", "prerentdb"); 

// Check connection
if($link === false){ die("ERROR: Could not connect. " . mysqli_connect_error()); }
//MySqli Select Query
$sql = "select * FROM payfile";
echo "<center>";echo date('m/d/y');echo "<br />";
$due=0;
  $prevbal="prevbal";
  $latechg="latechg";
   $secdep="secdep";
   $damage="damage";
$courtcost="courtcost";
      $nsf="nsf";
   $amtdue="amtdue";
   $amtpaid="amtpaid";
  $paidsum="paidsum";

$due = $prevbal + $latechg + $secdep + $damage + $courtcost + $nsf; // Warning: A non-numeric value encountered x 5 line 21
$amtdue = $amtdue + $due;  Warning: // A non-numeric value encountered x 1 line 22

// if no payment or partial payment, add $10 to latechg field and amount not paid to prevbal field
if ($amtpaid < $amtdue)  // Notice: Undefined variable: amtpaid
{ $latechg = $latechg + 10; $prevbal = $amtdue - $amtpaid;  }
// if payment = amtdue clear due
if ($amtpaid == $amtdue) // Notice: Undefined variable: amtpaid
{ $prevbal = 0; $latechg = 0; }
// if over-payment subtract over-payment
// from prevbal field
if ($ampaid > $amtdue )  // Notice: Undefined variable: amtpaid
{ $amtdue = $amtpaid  - $amtdue;  $prevbal = 0; $latechg = 0;  }
$secdep = 0; $damage = 0; $courtcost = 0; $nsf = 0;

// refresh every record - give every record the below values
$amtpaid = '0.00';
$hudpay = '0.00';
$datepaid = ' ';
$paidsum = '0.00';
$comments = ' ';

// Perform a query, check for error
if (!$mysqli -> query("UPDATE payfile SET // Undefined variable: mysqli 
Fatal error: Uncaught Error: Call to a member function query() on null 
 prevbal='$prevbal',latechg='$latechg', hudpay='$hudpay', amtpaid='$amtpaid', 
datepaid='$datepaid', comment='$comment', paidsum='$paidsum' 
where unit = $unit"));
mysqli_query($sql) or die(mysql_error());
?>

these are error messages:

Warning: A non-numeric value encountered in C:\xampp\htdocs\property\refreshpayments.php on line 21

Warning: A non-numeric value encountered in C:\xampp\htdocs\property\refreshpayments.php on line 21

Warning: A non-numeric value encountered in C:\xampp\htdocs\property\refreshpayments.php on line 21

Warning: A non-numeric value encountered in C:\xampp\htdocs\property\refreshpayments.php on line 21

Warning: A non-numeric value encountered in C:\xampp\htdocs\property\refreshpayments.php on line 21

Warning: A non-numeric value encountered in C:\xampp\htdocs\property\refreshpayments.php on line 21

Warning: A non-numeric value encountered in C:\xampp\htdocs\property\refreshpayments.php on line 22

Notice: Undefined variable: ampaid in C:\xampp\htdocs\property\refreshpayments.php on line 32

Notice: Undefined variable: mysqli in C:\xampp\htdocs\property\refreshpayments.php on line 44

Fatal error: Uncaught Error: Call to a member function query() on null  on line 44

[BC_Programmer]

#1) how to define variables as numeric(I've tried several examples(forums and manuals)

You assign them numeric values. You are assigning strings to variables, and then trying to add those strings together.
I'll answer your question with another question:

Code: [Select]

$prevbal="prevbal";

This assigns the string value "prevbal" to the $prevbal variable.

#2) how to add several variables together so they are known as numeric(they are all decimal 8,2 in the database)

So I take it you think your assignments are somehow pulling from the database? I do not know why you would have that impression. You need to perform a query, read the first row, and then assign the fields from that row to those variables.

#3) Please, someone explain the "Undefined variable: mysql".

$mysqli is undefined. You probably want the mysqli_query function.