mysql 引用php中变量查询
mysql 引用php中变量查询时，要加{}，比如
$start_time = '2019-01-01 13:50:42';
$end_time = '2019-04-06 00:00:00';
echo var_dump('2019-06-09 00:00:00'); //string datetime
$sql="SELECT * FROM test where timeall >= '{$start_time }' AND timeall <= '{$end_time }' ORDER BY ID DESC";
//$sql ="SELECT * FROM test WHERE UNIX_TIMESTAMP(timeall) >= UNIX_TIMESTAMP($start_time) AND UNIX_TIMESTAMP(timeall) <= UNIX_TIMESTAMP($end_time ) ORDER BY ID DESC";