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<?php
$query_date = '2010-02-04';
// First day of the month.
echo date('Y-m-01', strtotime($query_date));
// Last day of the month.
echo date('Y-m-t', strtotime($query_date));
xxxxxxxxxx
$date = '2023-09-20';
$date = date('Y-m-d', strtotime($date .' -1 day' ) );
'this will return the date of previous day'