Evaluating php code stored in database - php

Question

I have several strings stored in a database (yes, I know it's not the best practice, but I'm working with a system someone else designed and I cannot change it.)
For example, in my table called specialDates, I have a computedDate column that contains this:
date('d', strtotime("thursday, november ".date("Y")." + 3 weeks"))
This is pulled into my code and stored in a variable called $request['order_date'].
This, when used in standard PHP code, returns the date that Thanksgiving falls on in the current year. I need to pass the evaluated value of this (for this year - 2013 - the value is 28) to another query. But I can't seem to get the value to evaluate.
$query = 'SELECT count(orderID) as numberOfOrders FROM customer_orders WHERE customerID = ? AND orderDate = ?';
$param = array($request['customer_id'], eval($request['order_date']));
doesn't work. And when I just try to echo out the value to the screen, doing this:
echo eval($request['order_date']);
or this:
echo eval(" return \$request['order_date']; ");
just prints out the literal value of the string (i.e. date('d' etc.) rather than the expected evaluated value.
What am I doing wrong?
UPDATED
I tried AScherer's answer below, and although it does work when I just echo the value to the screen:
echo eval(" return {$request['order_date']}; ");
it does not work when I try to use the eval inside my array:
$param = array($request['customer_id'], eval("return {$request['order_date']}"));
How can I get this working so that the value I'm passing in the array is the actual value of 28, rather than the string pre-eval?

Answer 1

You were escaping the $request in your return part, which you dont want to do. This method should work, but id suggest adding return the the row in the database so u dont have to modify the eval
$sql = "SELECT customer_id, CONCAT( 'return ', order_date, ';' ) as function from customer_orders WHERE customerID = ? AND orderDate = ?";
$param = array( $request[ 'customer_id' ], eval( $request[ 'function '] ) );
---
OR
---
$evalData = eval(" return {$request['order_date']}; ");
$param = array($request['customer_id'], $evalData );

Answer 2

Yes, you can change it. If not to a sensible result, then to a useful result nontheless.
Your input data is a string:
date('d', strtotime("thursday, november ".date("Y")." + 3 weeks"))
This is an information to "calculate Thanksgiving of this year". You can set up a lookup table that detects this string and the needed function to execute:
$dateCalculations = array(
'date(\'d\', strtotime("thursday, november ".date("Y")." + 3 weeks"))' => function()
{
return date('d', strtotime("thursday, november ".date("Y")." + 3 weeks"));
}
'date(\'...whatever else is in the system...' => function(){}
// alias names also work
'thanksgiving' => function()
{
return date('d', strtotime("thursday, november ".date("Y")." + 3 weeks"));
}
);
You can then try to find the string from the database in the array and instantly have the function you need to call:
$thanksgiving = $dateCalculations[$dbvalue]();
From here you can go anywhere. Note that this will also work with the alias name "thanksgiving", so you might be able to replace it in the database if you know where else this braindead approach is also used... If not, at least you tried your best.