Adding a vaule to an existing value in a sql table

[TheStalker]

Hi i want to know how to add a set value to an existing value sotred in an sql table when a button is clicked on a php website. Can anyone point me in the right direction at all with a bit of code? many thanks.

[php_dave]

Sorry - I dont understand..

 

Do you mean you have a value stored in a table for example

 

Value

20

 

and want to be able to increment this value or make and adition to this value in the table..

 

If so - i think the way I would do it would be to pull the current value and then add the change in PHP then update the field in mysql but you may be able to do this directly with something like

 

Update my_table SET value = value + addition

 

This is not tested though

 

HTH

[trq]

Also, if the filed you wish to add to contains text you can use mysql's COCAT function.

 

UPDATE tbl SET fld = CONCAT(fld,'more text');

[TheStalker]

yes i have a value in a table for example 0.00 and want to add say 0.45 to the value in the table each time a button is clicked

[trq]

A simple example.

 

<form method="post">
  <input type="text" name="row">
  <input type="submit" name="submit" value="add">
</form>
<?php

if (isset($_POST['submit'])) {

  // connect to db.

  $row = mysql_real_escape_string($_POST['row']);
  $sql = "UPDATE tbl SET fld = fld+1 WHERE id = $row";
  if (mysql_query($sql)) {
    if (mysql_affected_rows()) {
      echo "$row updated</br >";
    }
  }
}

?>

[TheStalker]

thanks for all the replys ill explain in more detail ( i prob should have from the start)

 

i have a table called accounts that has customerID, Surname, newspaper and AmountOwing

 

when i click a button i want to have the value of a newspaper added to AmountOwing e.g

 

 

if newspaper = "sun" +0.35 AmountOwing

 

else if newspaper ="Times"  +0.45 AmountOwing

 

etc..........

 

 

 

 

[TheStalker]

<?php

$result = mysql_query("SELECT * FROM accounts");

 

while($row = mysql_fetch_array($result))

 

 

 

$value = $row['AmountOwing'];

 

echo $value;

 

if (['newspaper']="Sun");

{

+0.35 $value;

}

else if (['newspaper']="Times");

{

+0.45 $value;

}

 

echo $value;

?>