Question

$SQLString = "SELECT    
                count(score) as counts,
                score, month,
                date FROM persons  
                GROUP BY day, month, year 
            ORDER BY date asc";     

    $result = mysql_query($SQLString);   
    $num = mysql_num_rows($result);   


$data[0] = array('day','counts');       
    for ($i=1; $i<($num+1); $i++)
    {
        $data[$i] = array(substr(mysql_result($result, $i-1, "date"), 0, 10),
            (int) mysql_result($result, $i-1, "counts"));
    }   
    echo json_encode($data);

This outputs something like this:

[["day","counts"],["2012-01-20",1],["2012-02-06",1],["2012-11-16",2],["2013-04-13",1]] 

My problem is that I need that date values (eg. “2012-01-20”) in date type instead of string.

I really need your help…

Answer 1

MySQL date values ARE strings. If you stored them as plaintext, they’d be seen as integer subtractions, e.g.

 2012-01-02 -> 2012 minus 1 minus 2 -> 2009

Javascript has no native “date” strings. There’s only the Date object, which can’t be represented in a JSON string. If you want integers, you’ll have to store them as unix timestamps, e.g.

2012-01-20 00:00:00 -> 1327039200

However, note that Javascript uses milliseconds for its timestamp values, so you’d need

1327039200000

as the value to pass through.

Note that your code is highly inefficient. mysql_result is painfully slow, and ugly to work with. You could simply things greatly with

$sql = "SELECT COUNT(score) AS counts, unix_timestamp(yourdatefield) AS timestamp ...";

$data = array();
while($row = mysql_fetch_assoc($result)) {
   $timestamp = $row['timestamp'];
   $data[] = array($row['counts'], $row['timestamp'] * 1000);
}
echo json_encode($data);

then you can convert those timestamps to have JS date objects with

var d = new Date(1327039200000);