I need to be able to update a row in the database (price) by a percentage value which is entered either by typing into an input box or by up/down arrows.
I know I can update via a query directly by using
UPDATE table_name SET column_name=column_name*(100+percentage)/100I just have no idea where to start with php.
Any tips, hints or tutorials you could point me to. A google and github search has just given me a headache 
Thanks
It is still an update. In the model for that property, do the math,
$value = 55;
function formula($val)
{
return $val/100;
}
echo formula($value);sorry due to work comments I have not been able to get back to this but lets get it on.
I have 2 tables which are tbl_temp_products and tbl_temp_categories and the fields as below (there are more fields but not relevant to this question)
tbl_temp_products contains colums called id and categories
eg.
id - row value 1
categories - row values - 100175, 100575 (this is how they are stored in this table)
tbl_temp_categories
eg.
categories_id - row value 100175
categories_name - row value Mugs
categories_id - row value 100575
categories_name - row value Souvenirs & Seaside
I presume I need to join the tables with a query to be able to update the price by percentage by category in tbl_temp_products
I have the following code which creates a dropdown with the categories from tbl_temp_categories
[code] <?php
$sql = “SELECT categories_id, categories_name FROM tbl_temp_categories”;
$result = $conn->query($sql);
echo "<select name='categories_name' class='form-control'>";
while ($row = mysqli_fetch_array($result)) {
echo "<option value='" . $row['categories_name'] . "'>" . $row['categories_name'] . "</option>";
}
echo "</select>";
?>
Do I use a cross, inner, outer, left or right join as I am a bit confused on how to link the 2 tables.
I hope all the above made sense urgh
if you expect records that MUST have a corresponding set in both tables, use INNER JOIN. And read tutorials about the others.