I need help to create a function!

inventive

I need to create a function that automatically store a record.When i insert a new record of product,i want a function that can store all information of the record.So,when i login again to store a new record,which is the same product that i have store before,it will automatically show all information about (Harga Jualan,Harga Seunit,Peratus Keuntungan and Profit)that we have store before.It will detects by the Nama Produk.So,it will be more efficent.If the product was same which i store before,i dont have to insert all record.I hope someone can help me to codes a php function to save all information and we can call it back if we store a new record which is same name with the records in the system.We detect it from it name in Nama Produk.

I really hope someone can give me example of codes taht similiar to my problem.This is a code of Stock that i want to create a function that automatically save all information about products.

<? $stok=$_POST['stok'];
?>

<html>
<head>
<title>Terminal Computer Services :: STOK</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>
<script type="text/javascript">
function CalcPercnt(f) {
var val=f.peratuskeuntungan.options[f.peratuskeuntungan.selectedIndex].text
if (val == "")return false
var daTotal=(f.hargaseunit.value * (val / 100 + 1)).toFixed(2)
f.hargajualan.value = daTotal
f.profit.value=(daTotal-f.hargaseunit.value).toFixed(2)
}
</script>
<style type="text/css">
.ro{
background-color: royalblue;
color: white;
border: 2px solid skyblue;
}
</style>

   <a href="paparstok.php"><strong><font face="Verdana, Arial, Helvetica, sans-serif"><font color ="black"></font></font>
   <h1><p align="center">STOK</h1></strong></a></p>

    </p>
  </td>
  </tr>
</table><br><br><br><br>

<tr>
<td width="41%"><font color="#FFFFFF"><h3>Nama Produk:</h3></font></td>
<td width="29%"> <input name="namaproduk" type="text" size="25"></td>
</tr>

<tr>
<td width="29%"><font color="#FFFFFF"><h3>Harga Seunit:</h3><td width="71%"><input name="hargaseunit" type="text" size="25"></td>
</tr>
<tr>

<td width="29%"><font color="#FFFFFF"><h3>Peratus Keuntungan:</h3></td><td><select name="peratuskeuntungan" id="peratus">
<option>5</option>
<option>10</option>
<option>15</option>
<option>20</option>
<option>25</option>
<option>30</option> 
</select></td>

</tr>
<tr>
<td width="41%"><font color="#FFFFFF"><h3>Harga Jualan:</h3><td width="30%"><input name="hargajualan" type="text" readonly class="ro" size="25"></td>
</tr>

<td width="41%"><font color="#FFFFFF"><h3>Profit:</h3><td width="30%"><input name="profit" type="text" readonly class="ro" size="25"></td>

</tr>
<br><br><br>
<tr><td height="95"> </td>
<td><input onClick="CalcPercnt(this.form)" type="button" value="Calculate">
<input type="reset" value="Clear"></td>
</tr>

<td><font color="#FFFFFF"><h3>Tarikh<em>(dd/mm/yy)</em>:</h3></font></td><td>

<tr><td height="95"> </td>
<td><input type="submit" name="Submit" value="Submit">
<input type="reset" name="Submit2" value="Reset"></td>
</tr>
</form></table>
<br><br>
<a href="produk.php"><strong><font face="Verdana, Arial, Helvetica, sans-serif"><font color ="black"></font></font>
<h2><p align="center">PRODUK</h2></strong></a></p>
</td>
</tr>
</table>
</body>
</html>