我尝试了很多方法，但无法解决：
select count(so.name) as no
from sale_order so
left join sale_order_line sl on sl.order_id = so.id
group by sl.product_id, so.partner_id
数据：
SO----------------------order line
1-----------------------11 & 12
2-----------------------21
3-----------------------31
4-----------------------41 & 42
我需要打印计数（so.name）= 4