mybatis plus 支持多表关联 多租户查询，也支持自定义sql ,例如：SELECT kc.id, kc.name, kc.description, kc.avatar, kc.join_type, kc.price, kc.valid_days, kc.bg_image, kc.is_open, kc.enable_custom_nav, kc.nav_list, kc.create_dept, kc.create_by, kc.create_time, kc.update_by, kc.update_time, COUNT(DISTINCT kcm.user_id) AS member_count, COUNT(DISTINCT kp.id) AS post_count FROM kl_circle kc LEFT JOIN kl_circle_member kcm ON kc.id = kcm.circle_id AND kcm.tenant_id = '000000' LEFT JOIN kl_post kp ON kc.id = kp.circle_id AND kp.tenant_id = '000000' WHERE kc.id = ? AND kc.tenant_id = '000000' GROUP BY kc.id

tenant_id 这个字段都是自己框架加上的