UPDATE wp_posts SET post_date = DATE_FORMAT(FROM_UNIXTIME(UNIX_TIMESTAMP('2016-03-01') + FLOOR(0 + (RAND() * 63072000))), '%Y-%m-%d');
UPDATE wp_posts SET post_date_gmt = DATE_FORMAT(FROM_UNIXTIME(UNIX_TIMESTAMP('2016-03-01') + FLOOR(0 + (RAND() * 63072000))), '%Y-%m-%d');
UPDATE wp_posts SET post_modified = DATE_FORMAT(FROM_UNIXTIME(UNIX_TIMESTAMP('2016-03-01') + FLOOR(0 + (RAND() * 63072000))), '%Y-%m-%d');
UPDATE wp_posts SET post_modified_gmt = DATE_FORMAT(FROM_UNIXTIME(UNIX_TIMESTAMP('2016-03-01') + FLOOR(0 + (RAND() * 63072000))), '%Y-%m-%d');