解决SQL Server语句中括号未同时应用这两个条件的最佳做法是什么？

这个WHERE子句返回数据，就好像括号不在那里一样。使用

“批发”

或

“餐厅”

返回数据的最佳做法是什么，但不能同时使用这两种方法

SELECT fruit, price, market
FROM fruit_data
WHERE
   fruit = 'banana'
   AND (vendor != 'wholesale' AND market != 'restaurant')

我认为我的解决方案不是最佳实践，尽管它可以：

   AND (
       (vendor != 'wholesale' AND market = 'restaurant')
       OR (vendor = 'wholesale' AND market != 'restaurant')
       OR (vendor != 'wholesale' AND market != 'restaurant')
       )

---

您的

where

子句与

fruit = 'banana' AND vendor <> 'wholesale' AND market <> 'restaurant'

---

您的

where

子句与

fruit = 'banana' AND vendor <> 'wholesale' AND market <> 'restaurant'

…包含“批发”或“餐厅”的数据，但不能同时包含两者

经典方法：

select      fruit, price, market
from        fruit_data
where       fruit = 'banana'
and         (vendor = 'wholesale' or market = 'restaurant')
and         not (vendor = 'wholesale' and market = 'restaurant')

select      fruit, price, market
from        fruit_data
cross apply (select 
                isWs = iif(vendor = 'wholesale', 1, 0),
                isRst = iif(market = 'restaraunt', 1, 0)
            ) ap
where       fruit = 'banana'
and         isWs + isRst = 1;

更为算术的方法：

select      fruit, price, market
from        fruit_data
where       fruit = 'banana'
and         (vendor = 'wholesale' or market = 'restaurant')
and         not (vendor = 'wholesale' and market = 'restaurant')

select      fruit, price, market
from        fruit_data
cross apply (select 
                isWs = iif(vendor = 'wholesale', 1, 0),
                isRst = iif(market = 'restaraunt', 1, 0)
            ) ap
where       fruit = 'banana'
and         isWs + isRst = 1;

…包含“批发”或“餐厅”的数据，但不能同时包含两者

经典方法：

select      fruit, price, market
from        fruit_data
where       fruit = 'banana'
and         (vendor = 'wholesale' or market = 'restaurant')
and         not (vendor = 'wholesale' and market = 'restaurant')

select      fruit, price, market
from        fruit_data
cross apply (select 
                isWs = iif(vendor = 'wholesale', 1, 0),
                isRst = iif(market = 'restaraunt', 1, 0)
            ) ap
where       fruit = 'banana'
and         isWs + isRst = 1;

更为算术的方法：

select      fruit, price, market
from        fruit_data
where       fruit = 'banana'
and         (vendor = 'wholesale' or market = 'restaurant')
and         not (vendor = 'wholesale' and market = 'restaurant')

select      fruit, price, market
from        fruit_data
cross apply (select 
                isWs = iif(vendor = 'wholesale', 1, 0),
                isRst = iif(market = 'restaraunt', 1, 0)
            ) ap
where       fruit = 'banana'
and         isWs + isRst = 1;

“批发”或“餐厅”数据，但不是两者都有

SELECT fruit, price, market
FROM fruit_data
WHERE
   fruit = 'banana'
   AND (vendor != 'wholesale' AND market != 'restaurant')

这不是：

vendor='wholesale'或market='restaurant'和（而不是（vendor='wholesale'和market='restaurant'））

“批发”或“餐厅”数据，但不是两者都有

SELECT fruit, price, market
FROM fruit_data
WHERE
   fruit = 'banana'
   AND (vendor != 'wholesale' AND market != 'restaurant')

这不是：

vendor='wholesale'或market='restaurant'和（NOT（vendor='wholesale'和market='restaurant'））

“这个WHERE子句返回数据，就好像括号不在那里一样。”这是值得怀疑的，你的理解是错误的。你想在这里干什么？样本数据和预期结果将帮助我们帮助您。您的“解决方案”看起来相当于

而不是（供应商='批发'和市场='餐厅'）

或

和（供应商！='批发'或市场！='餐厅'）

。拿你的选择来说。“这个WHERE子句返回数据，就好像括号不在那里一样。”这是值得怀疑的，这是你理解错误的地方。你想在这里干什么？样本数据和预期结果将帮助我们帮助您。您的“解决方案”看起来相当于

而不是（供应商='批发'和市场='餐厅'）

或

和（供应商！='批发'或市场！='餐厅'）

。你挑吧。