PHP-MYSQL: Converting Unix Timestamp to DateTime and vice versa

Question

im using php 5.4.6 and MySQL 5.5.29 and I get trouble by converting a UNIX TIMESTAMP to MYSQL DATETIME and vice versa. Mysql and php wun on the same local machine.

I have a simple mysql table

CREATE TABLE Entry(
id SERIAL PRIMARY KEY,
created DATETIME NOT NULL);

To insert data I use php PDO and mysql NOW(). This works fine, the correct datetime is stored in the database.

My plan is to work with unix timestamps on client side (php & mysql on server side).

So I would like to deliver unix timestamps to my client. Therefore I use MySql UNIX_TIMESTAMP() function to convert it directly in the query.

So a sample query looks like this:

SELECT created, UNIX_TIMESTAMP(created) AS TS FROM Entry

The result: created = 2013-02-14 20:47:35 TS = 1360871255

So now I want to do the other way, I pass the a UNIX Timestamp, and want to compare it with Entries in my Database. Unfortunetly Im not able to write a PHP script that works. I don't know why, but when I m passing the same timestamp (1360871255) to PHP I do not get 2013-02-14 20:47:35 with this method:

public static function toDateTime($unixTimestamp){
    return date("Y-m-d H:m:s", $unixTimestamp);
}

When I call toDateTime(1360871255) will return 2013-02-14 20:02:35 which is not the original DateTime.

I know, I dont need to format 1360871255 to a Y-m-d H:m:s to use it in MYSQL, but 1360871255 seems not to be the time that I expected (and MYSQL UNIX_TIMESTAMP has returned).

What I want to do is a simple query that shows me Entries that are older than a certain timestamp, something simple like this:

SELECT * FROM Entry WHERE created < 1360871255

but as I mentioned before, the query result is not the expected, because 1360871255 seems not to be the correct time.

I do not specify any special timezone for the mysql connection in php.

Any suggestions?

Answer 1

Your date format is wrong... i is for minute, not m (months).

return date("Y-m-d H:i:s", $unixTimestamp);

A few side notes:

• There's no need to re-assign, i.e. $unixTimestamp = $unixTimestamp;
• Since you're using PHP > 5.3. you may be interested in the new DateTime object.

Answer 2

The problem lies in the function you wrote:

return date("Y-m-d H:m:s", $unixTimestamp);

You specify month(m) in both the date and time portions. You should replace the second m with i, the correct flag for hours when using date() in PHP.

return date("Y-m-d H:i:s", $unixTimestamp);

Depending on your needs you might find the PHP function strtotime() useful enough.

Answer 3

Why not simply use the FROM_UNIXTIME function in mysql ?

Answer 4

function format_date($str) {
    $month = array(" ", "Jan", "Feb", "Mar", "Apr", "May", "June", "July", "Aug", "Sep", "Oct", "Nov", "Dec");
    $y = explode(' ', $str);
    $x = explode('-', $y[0]);
    $date = "";    
    $m = (int)$x[1];
    $m = $month[$m];
    $st = array(1, 21, 31);
    $nd = array(2, 22);
    $rd = array(3, 23);
    if(in_array( $x[2], $st)) {
            $date = $x[2].'st';
    }
    else if(in_array( $x[2], $nd)) {
            $date .= $x[2].'nd';
    }
    else if(in_array( $x[2], $rd)) {
            $date .= $x[2].'rd';
    }
    else {
            $date .= $x[2].'th';
    }
    $date .= ' ' . $m . ', ' . $x[0];

    return $date;
}

Answer 5

nothing of both. you should save the timestamp as an INT or BIGINT because if you use the TIMESTAMP format of mysql you will never ever get it back to an int. You can only get something like this 1970-01-01 01:00:00.