PHP fill array with sum of mysql column

Just take out the WHERE clause, and you'll get results for every week.

$result = mysql_query("SELECT week, SUM(products) AS total 
  FROM production GROUP BY week");

The results will be returned as successive rows from the result set, and you can put them into an array:

$sum_by_week = array();
while ($row = mysql_fetch_assoc($result)) {
  $sum_by_week[$row["week"]] = $row["total"];
}

PS: You didn't ask for this, but you should be aware that the mysql_* functions are being deprecated. You should start using the mysqli functions or PDO for new PHP applications. Only if you're just maintaining an existing application is it worthwhile to continue using the old mysql_* functions.

Apologies in advance for using mySQL instead of another extension. ;-)

<?php // RAY_temp_rowan.php
error_reporting(E_ALL);
echo "<pre>";


// CONNECTION AND SELECTION VARIABLES FOR THE DATABASE
$db_host = "localhost"; // PROBABLY THIS IS OK
$db_name = "??";        // GET THESE FROM YOUR HOSTING COMPANY
$db_user = "??";
$db_word = "??";

// OPEN A CONNECTION TO THE DATA BASE SERVER
// MAN PAGE: http://php.net/manual/en/function.mysql-connect.php
if (!$db_connection = mysql_connect("$db_host", "$db_user", "$db_word"))
{
    $errmsg = mysql_errno() . ' ' . mysql_error();
    echo "<br/>NO DB CONNECTION: ";
    echo "<br/> $errmsg <br/>";
}

// SELECT THE MYSQL DATA BASE
// MAN PAGE: http://php.net/manual/en/function.mysql-select-db.php
if (!$db_sel = mysql_select_db($db_name, $db_connection))
{
    $errmsg = mysql_errno() . ' ' . mysql_error();
    echo "<br/>NO DB SELECTION: ";
    echo "<br/> $errmsg <br/>";
    die('NO DATA BASE');
}
// IF WE GOT THIS FAR WE CAN DO QUERIES


// CREATING A TABLE
$sql = "CREATE TEMPORARY TABLE my_table (
        _key INT         NOT NULL AUTO_INCREMENT,
        shift    INT NOT NULL DEFAULT 0,
        line     INT NOT NULL DEFAULT 0,
        products INT NOT NULL DEFAULT 0,
        week     INT NOT NULL DEFAULT 0,
        PRIMARY KEY(_key)  )";
$res = mysql_query($sql);

// IF mysql_query() RETURNS FALSE, GET THE ERROR REASONS
if (!$res)
{
    $errmsg = mysql_errno() . ' ' . mysql_error();
    echo "<br/>QUERY FAIL: ";
    echo "<br/>$sql <br/>";
    die($errmsg);
}



// LOAD UP THE TABLE
mysql_query('INSERT INTO my_table (shift, line, products, week) VALUES (1,2,4000, 1)') or die(mysql_error());
mysql_query('INSERT INTO my_table (shift, line, products, week) VALUES (1,4,4000, 1)') or die(mysql_error());

mysql_query('INSERT INTO my_table (shift, line, products, week) VALUES (1,2,4000, 2)') or die(mysql_error());
mysql_query('INSERT INTO my_table (shift, line, products, week) VALUES (1,4,5000, 2)') or die(mysql_error());

mysql_query('INSERT INTO my_table (shift, line, products, week) VALUES (1,2,4000, 3)') or die(mysql_error());
mysql_query('INSERT INTO my_table (shift, line, products, week) VALUES (1,4,6000, 3)') or die(mysql_error());


// MAKING A SELECT QUERY AND TESTING THE RESULTS
$sql = "SELECT week, SUM(products) as sump FROM my_table GROUP BY week ORDER BY week ASC";
$res = mysql_query($sql);

// IF mysql_query() RETURNS FALSE, GET THE ERROR REASONS
if (!$res)
{
    $errmsg = mysql_errno() . ' ' . mysql_error();
    echo "<br/>QUERY FAIL: ";
    echo "<br/>$sql <br/>";
    die($errmsg);
} // IF WE GET THIS FAR, THE QUERY SUCCEEDED AND WE HAVE A RESOURCE-ID IN $res SO WE CAN NOW USE $res IN OTHER MYSQL FUNCTIONS



// ITERATE OVER THE RESULTS SET TO SHOW WHAT WE SELECTED
while ($row = mysql_fetch_assoc($res))
{
    $out[$row["week"]] = $row["sump"];
}

var_dump($out);