How to add Values

[Icewolf]

Hi

I want to say thank you all for your help. I have one more question. How do I add a field from a form to a field in mysql database. What I want is if the field on the form has 200 and the field in the database has 200 then the field updates to 400 when I hit the submit button. What I am not sure of do I need to query the database first and then add them together?

 

Here is what I have for now.

$query = "UPDATE Points_Rewards Set Bank = '$bank', Reward_1 = ('$reward1' + Reward_1), Reward_2 = ('$reward2' + Reward_2), Reward_3 = ('$reward3' + Reward_3) WHERE Member_ID = '$memid'";
$result = mysql_query($query) or die(mysql_error());

 

[Jessica]

Set Field = field+200 is a valid update.

[Icewolf]

What happens is a person enters a value to a text box on a form and then what I want to do is just add that value to what is already in the database.

[Jessica]

And as I said. The query "UPDATE `table` SET `column`=`column`+200 WHERE `id`=1" is a perfectly good query. You don't need to select it first. Just update it.

[Yohanne]

use variable to catch-up your 200 value

[Icewolf]

Thank you for your response I understand what you are saying. Maybe I didn't say what I need to correct way. Right now when the person goes to this webpage I have for text boxes where the user can put in any number in. From that I want to take the value from the webpage and add it to the value that is already in the database. I was just saying the 200 as an example.

[topcat]

The above response is still the way to go just replace the 200 with the value from the form field:

$value = $_POST['the_id_of_the_formfield']; or however you retrieve the value from the form. I would do some checking here to make sure that the value really is an integer to avoid sql injection attacks. such as:

 

if(!is_int($value)){ show a messsage to user saying it must be an integer and exit" }
 

otherwise add it to the existing database field

$sql = "UPDATE `table` SET `column`=`column`+ $value WHERE `id`=1"; (obviously you would have to dynamically set the id.

hope that helps

Edited April 4, 2013 by topcat

[Jessica]

Thank you for your response I understand what you are saying. Maybe I didn't say what I need to correct way. Right now when the person goes to this webpage I have for text boxes where the user can put in any number in. From that I want to take the value from the webpage and add it to the value that is already in the database. I was just saying the 200 as an example.

Did you try using a little logic to look at what I posted and what you posted, and figure out how to USE what I posted?