hello everyone, i want to + and - numbers from the money feild,

so if i click the add $10 and say i have $3 it will == $13
and if i have $200 and click add $10 it will == $210

so with that code

(mysql_query("UPDATE tablename SET field = '$money' WHERE id = '$user_id'"); )

i can only make it set to ten.

SET field = field + $money

See post below by chris.

What Chris is trying to explain is:

You need to get the exisiting ammount from the table cell:

mysql_query("SELECT field FROM table WHERE id =  '$user_id'");

Then you put the vars together, I would do this before the query:

PHP Code:

//Best to perform some checks, make sure the value is a number...
if(is_numeric($queryresult['field']){
      $money = $queryresult['field'] + '10';
} 


Then perform the query:

mysql_query("UPDATE tablename SET field = '$money' WHERE id =  '$user_id'");

But you don't NEED to retrieve the value then add it and return it to the database.
That's very inefficient and wasteful of processing time and resources.

USE the database server for what it is good at.

Why make two queries when one will suffice???

Keep data calculations ON THE dB SERVER

PHP Code:

mysql_query("UPDATE tablename SET field = field + $money WHERE id =  '$user_id'"); 


Will add the variable to the field in a single query

ahha, my bad chris, didnt know that. Could come in handy

Sorry i got confused with the layout of the query you wrote and (wrongly) assumed it was the logic not the process.

Thanks!

Yep it's a common thing, especially with programmers who have learnt on MySql alongside and in conjunction with PHP.

It simply isn't understood or appreciated just how powerful database servers and Structured Query Language truly is.
The idea that all DB servers to is store and retrieve data that then has to be manipulated in server code is all too prevalent.

I am terrible for this (read, lazy), I generally use PHP to do all the manipluation etc and only use SELECT, INSERT, UPDATE and DELETE in thier most basic forms.

I really should read up on the more advanced/less basic querys and methods.

Aye, you would be surprised at what can be done in a single query, even moreso when you start looking at stored procedures.

Originally Posted by chrishirst

even moreso when you start looking at stored procedures.

True - I'm currently getting into using the PDO Data Abstraction Layer, cool stuff!

Do either of you have an suggested or reccomended reading about stored procedures?

Ive heard of them however they were being used with .NET and I have no knowledge of .NET

http://msdn.microsoft.com/en-us/libr...SQL.80%29.aspx

Thanks Chris