I am trying to run the mysql query to count the record of last one month , Here is the query ,

 $school_count_last_month = get_var("SELECT COUNT(*) FROM $wpdb->posts WHERE post_date >= DATE_ADD(LAST_DAY(DATE_SUB(NOW(),INTERVAL 2 MONTH)),INTERVAL 1 DAY) AND post_date <= DATE_SUB(NOW(),INTERVAL 1 MONTH)"); 

As this query working in phpmyadmin but when I tried to load my website not show anything.

Although , I have tried another sql queries in same page,but they are working perfectly .

Thanks