令我困惑的sql语句

Question

select Type,tb_Commodity.CommodityName, tb_Company.CompanyName,count(tb_Reckoning.CommodityId)+1 as 借款次数 
from tb_Company,tb_Stock,tb_Commodity ,tb_Reckoning 
where tb_Commodity.id=tb_Stock.CommodityId and tb_Company.id=tb_Stock.CompanyId and tb_Stock.Type='进货信息' and tb_Reckoning.CommodityId=tb_Stock.id
group by tb_Reckoning.CommodityId 

Answer 1

select tb_Stock.Type,tb_Commodity.CommodityName, 
tb_Company.CompanyName,count(tb_Reckoning.CommodityId)+1 as 借款次数 
from tb_Company,tb_Stock,tb_Commodity ,tb_Reckoning 
where tb_Commodity.id=tb_Stock.CommodityId 
and tb_Company.id=tb_Stock.CompanyId 
and tb_Stock.Type='进货信息' 
and tb_Reckoning.CommodityId=tb_Stock.id 
group by tb_Stock.Type,tb_Commodity.CommodityName, 
tb_Company.CompanyName