Hello

A query for Posts module:

SELECT * FROM `bx_posts_posts` AS `tp` 
LEFT JOIN `sys_privacy_groups_custom` AS `tgc` ON `tp`.`id`=`tgc`.`content_id` AND `tp`.`author`=`tgc`.`profile_id` AND `tgc`.`object`='bx_posts_allow_view_to'
LEFT JOIN `sys_privacy_groups_custom_members` AS `tgcm` ON `tgc`.`id`=`tgcm`.`group_id` AND `tgcm`.`member_id` IN ('B', 'C')
WHERE `tp`.`author`='A' AND `tp`.`allow_view_to`='6'