[SOLVED] Adding Values, how is it done?

[nitation]

Hello people,

 

I can insert a value for a field named amount in my database, what i wanna do now is to add another value and it sum it up. My question is how do i go about it? do i insert a new value in the amount field on another row and add it? if yes, how do i do that in php.

 

Thanks in advance

[lemmin]

This SQL should work.

"UPDATE Table SET Amount = Amount + $newAmount";

[nitation]

Thank you Lemmin. It worked

[nitation]

@lemmin

 

The code you gave me worked fine. But the question is if i wanna remove the value i added new, how would it reverse to the first value entered.

 

Thanks in advance

[nitation]

Guys i hope my question is clear

[lemmin]

There wouldn't be a way to reverse it without knowing how much you added. If you keep the value somewhere, the same code would work with subtraction:

"UPDATE Table SET Amount = Amount - $newAmount";

[nitation]

@lemmin

 

You said if i keep the code somewhere. How can that be done. Do i need to insert each value for amount on a new row and sum it up or what. Please give me a rough idea on how to carry it out.

 

Thanks in advance

[lemmin]

It depends on how long you need to keep the old value. If it can only be changed while the user is logged in, but not after he/she has logged out once, then you can save the number in a session. If the value may be changed at a later time, the best way would probably be to keep the value in your database, like you said.

[nitation]

@lemmin,

 

Thank you for your reply. The question now is; if am trying to insert an amount value for a user using an HTML form that will be stored in a database. Do i need to create another HTML form to add another value before they can be summed up. The reason am asking this is because, if i will be using the same HTML form to add the 1st and second value, how do i query the database to do the addition.

 

I hope am clearer