sql server 2008 - Writing date to SQL from php, date is changed -

i have code in php 5.4 creating record in sql server 2008 r2. php code creates date:

$date = date("y-m-d"); 

which yeilds:

'2015-06-23' 

that date used in query sql server:

$insert = 'insert adattend (adenrollschedid, adenrollid, date, starttime, attend, absent, unittype, status, comment, excused, modflag, userid, dateadded, datelstmod, adclassattendid, type)         values ('.$adenrollschedid.','.$adenrollid.','.$date.',\'1899-12-30 07:00:00.000\','.$present.','.$absent.',\'m\',\'a\',\''.$comment.'\',0,\'a\','.$instructorid.         ','.$date.','.$date.','.$adclassattendid.',\'a\')'; 

the query seems work fine. record inserted should be. when check record in table dates are:

 '1905-06-23 00:00:00.000' 

so question is, why altering 2015 1905?

insert escape quotes or use double quotes in single quotes

$insert = 'insert adattend (adenrollschedid, adenrollid, date, starttime, attend, absent, unittype, status, comment, excused, modflag, userid, dateadded, datelstmod, adclassattendid, type)         values ('.$adenrollschedid.','.$adenrollid.',\''.$date.'\',\'1899-12-30 07:00:00.000\','.$present.','.$absent.',\'m\',\'a\',\''.$comment.'\',0,\'a\','.$instructorid.         ','.$date.','.$date.','.$adclassattendid.',\'a\')'; 

or

$insert = 'insert adattend (adenrollschedid, adenrollid, date, starttime, attend, absent, unittype, status, comment, excused, modflag, userid, dateadded, datelstmod, adclassattendid, type)         values ('.$adenrollschedid.','.$adenrollid.',"'.$date.'",\'1899-12-30 07:00:00.000\','.$present.','.$absent.',\'m\',\'a\',\''.$comment.'\',0,\'a\','.$instructorid.         ','.$date.','.$date.','.$adclassattendid.',\'a\')';