Variables within Variables

[mdavis00]

I have created a simple database abstraction layer for an application I am working on. In order to deal with differences in SQL syntax between database servers, I have decided to aggregate all of my queries together (this also supports code reuse)--see this thread for more info. However, I'm running into two problems. Basically, I need to store a variable name within an array and then have that variable expanded later. Here's some simplified code to illustrate:

class DB{
    function execute_query($query){
         #Pretend all the code to run a query is here...
    }

    function queries(){
        $queries = array(
            0 => "SELECT * FROM users WHERE username='$username'",
            1 => "Some other query",
        );
        return $queries;
    }
}

class Something{
    function get_user($username){
        $DB = new DB;
        $queries = $DB->queires();
        $result = $DB->execute_query($queries[0]);
        return $result;
    }
}

$Cheetohs = new Something;
$username = "Chester";
$user_data = $Cheetohs->get_user($username); 

The two problems I am running into are:

(1) php tries to expand the variable $username before storing it as part of the string in the array. I need it to be stored as '$username' in the array and I have no idea how to prevent php from trying to expand it. In the example above, PHP would throw an error saying that $username was undefined.

(2) Assuming that the first problem is addressed, then $username within $queries[0] isn't expanded when $queries[0] is included as an argument for my query function. Instead of passing this string to my DB server: "SELECT * FROM users WHERE username='Chester'", it would pass "SELECT * FROM users WHERE username='$username'". I think writing like this may fix that problem:

$result = execute_query(eval($queries[0])); 

But I haven't been able to test it because of the first issue.

So, what do you think? Is this just not going to work at all? Any ideas for how I can achieve this? THANKS!

[logic_earth]

Change your quote in the array to single quotes

array(
     'SELECT * FROM users WHERE username="$username"',
     '...'
); 

Also you do not need to do 0 => '' 1 => '' since by default those are the keys.

I try to use single quotes for every string that doesn't need to expand variables or anything else but a string.

[mdavis00]

Thanks Logic_Earth, that worked perfectly. Now I can be on to troubleshooting problem #2 with using eval() to try and expand the variable within the array...