2025-01-03职业生涯最复杂sql记录SELECTteaching_activity_comment_data.*,user_info.avatar,liveclass_relation_id.related_type,COALESCE(user_info.user_name,teaching_activity_visitor.name)asuser_name,COALESCE(user_info.login_name,teaching_activity_visitor.login_name)aslogin_nameFROM