<?

$A=
preg_split("/[\r\n]+/",
<<<'EOD'
2017-03-19 02:30:00
2017-03-19 02:30:00
2017-03-19 21:00:00
2017-03-19 23:15:00
2017-03-19 23:30:00
2017-03-19 00:00:00
2017-03-19 00:00:00
EOD
);

sort($A);
print_r($A);