mysql - sql查询返回不正确的结果

Question

我有一个 mysql 数据库，其中存储了一些产品的报价文件，这些产品清楚地定义了每种产品的价格，还有一个合同表，用于存储合同详细信息以及它所属的客户代码和报价代码。我有以下查询，看看报价单的总价是多少写在发票上：

select
   sum(sqproducts.price * sqproducts.quantity) as 'total-price',
   squotations.currency as 'currency'
from
  sqproducts,
  ccontracts,
  squotations
where 
  sqproducts.contracted=1
  AND squotations.code=sqproducts.quotation_code
  AND sqproducts.quotation_code=ccontracts.squotation_code
  AND sqproducts.quotation_code='QUOT/2012/1'
group by
  currency

Answer 1

它是盲目的，试试这个：

select
   sum(sqproducts.price * sqproducts.quantity) as 'total-price',
   squotations.currency as 'currency'
from
  sqproducts 
inner join squotations on (squotations.code=sqproducts.quotation_code)
inner join ccontracts on (sqproducts.quotation_code=ccontracts.squotation_code)

where 
  sqproducts.contracted=1
  AND sqproducts.quotation_code='QUOT/2012/1'
group by
  squotations.currency