php - My date is not saving correctly to MySQL in the datetime format -

i having problem saving dates mysql. when add datetime fields save correctly

2014-04-08 09:24:00

but when update data script below on rights datetime field with

0000-00-00 00:00:00

then if update second time correct date saves correctly. if update else on page saves

0000-00-00 00:00:00

again. appreciated. or maybe should go saving string rather datetime

$signstart , $signend date fields saving

 $stmt = $db->prepare("insert signings(signstart,signend,custid,contact,samount,prtamount,faxamount,ordern,fname,lname,street1,street2,city,state,zip,hphone,cphone,wphone,fax,email,coname,coworkphone,pid,invoicenumber,loannumber)values(?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)");              $stmt->bindparam(1, $_post['signstart'], pdo::param_str, 20);             $stmt->bindparam(2, $_post['signend'], pdo::param_str, 20);             $stmt->bindparam(3, $_post['custid'], pdo::param_str, 250);             $stmt->bindparam(4, $_post['contact'], pdo::param_str, 250);             $stmt->bindparam(5, $_post['samount'], pdo::param_int, 11);             $stmt->bindparam(6, $_post['prtamount'], pdo::param_int, 11);             $stmt->bindparam(7, $_post['faxamount'], pdo::param_int, 11);             $stmt->bindparam(8, $_post['ordern'], pdo::param_str, 250);             $stmt->bindparam(9, $_post['fname'], pdo::param_str, 250);             $stmt->bindparam(10, $_post['lname'], pdo::param_str, 250);             $stmt->bindparam(11, $_post['street1'], pdo::param_str, 250);             $stmt->bindparam(12, $_post['street2'], pdo::param_str, 250);             $stmt->bindparam(13, $_post['city'], pdo::param_str, 250);             $stmt->bindparam(14, $_post['state'], pdo::param_str, 250);             $stmt->bindparam(15, $_post['zip'], pdo::param_str, 250);             $stmt->bindparam(16, $_post['hphone'], pdo::param_str, 250);             $stmt->bindparam(17, $_post['cphone'], pdo::param_str, 250);             $stmt->bindparam(18, $_post['wphone'], pdo::param_str, 250);             $stmt->bindparam(19, $_post['fax'], pdo::param_str, 250);             $stmt->bindparam(20, $_post['email'], pdo::param_str, 250);             $stmt->bindparam(21, $_post['coname'], pdo::param_str, 250);             $stmt->bindparam(22, $_post['coworkphone'], pdo::param_str, 250);             $stmt->bindparam(23, $_post['pid'], pdo::param_int, 11);             $stmt->bindparam(24, $invoicenumber, pdo::param_int, 11);             $stmt->bindparam(25, $_post['loannumber'], pdo::param_str, 250);             $stmt->execute();    $sql = "update signings set         pid = ?,        signstart = ?,         signend = ?,        custid = ?,          contact = ?,        faxamount = ?,          samount = ?,        prtamount = ?,         faxamount = ?,        ordern = ?,        loannumber = ?,        fname = ?,        lname = ?,        street1 = ?,        street2 = ?,        city = ?,        state = ?,        zip = ?,        hphone = ?,        cphone = ?,        wphone = ?,        fax = ?,        email = ?,        coname = ?,        cocellphone = ?,        coworkphone = ?        id = ?";         $stmt = $db->prepare($sql);         $stmt->bindvalue('1', $_post['pid'], pdo::param_int);         $stmt->bindvalue('2', $_post['signstart'], pdo::param_str);         $stmt->bindvalue('3', $_post['signend'], pdo::param_str);         $stmt->bindvalue('4', $_post['custid'], pdo::param_str);         $stmt->bindvalue('5', $_post['contact'], pdo::param_str);         $stmt->bindvalue('6', $_post['faxamount'], pdo::param_int);         $stmt->bindvalue('7', $_post['samount'], pdo::param_int);         $stmt->bindvalue('8', $_post['prtamount'], pdo::param_int);         $stmt->bindvalue('9', $_post['faxamount'], pdo::param_int);         $stmt->bindvalue('10', $_post['ordern'], pdo::param_str);         $stmt->bindvalue('11', $_post['loannumber'], pdo::param_str);         $stmt->bindvalue('12', $_post['fname'], pdo::param_str);         $stmt->bindvalue('13', $_post['lname'], pdo::param_str);         $stmt->bindvalue('14', $_post['street1'], pdo::param_str);         $stmt->bindvalue('15', $_post['street2'], pdo::param_str);         $stmt->bindvalue('16', $_post['city'], pdo::param_str);         $stmt->bindvalue('17', $_post['state'], pdo::param_str);         $stmt->bindvalue('18', $_post['zip'], pdo::param_str);         $stmt->bindvalue('19', $_post['hphone'], pdo::param_str);         $stmt->bindvalue('20', $_post['cphone'], pdo::param_str);         $stmt->bindvalue('21', $_post['wphone'], pdo::param_str);         $stmt->bindvalue('22', $_post['fax'], pdo::param_str);         $stmt->bindvalue('23', $_post['email'], pdo::param_str);         $stmt->bindvalue('24', $_post['coname'], pdo::param_str);         $stmt->bindvalue('25', $_post['coworkphone'], pdo::param_str);         $stmt->bindvalue('26', $_post['cocellphone'], pdo::param_str);         $stmt->bindvalue('27', $_post['id'], pdo::param_int);         $stmt->execute(); 

are saying insert statement in code works, update statement doesn't work right?

one suggestion not update fields don't need to, if need update those, format coming in via $_post['signstart'] in post statement? can print out , make sure it's valid format insertion?