SQL Server在/或准确性/上下文中

我的_表中有以下列：

客户id、交易日期、店铺名称、交易id

如果我写：

SELECT DISTINCT customer_id, COUNT(DISTINCT transaction_id) as transaction_count
FROM my_table
WHERE shop_name = 'A'
OR shop_name = 'B'
AND transaction_date > 'yyyy-mm-dd'
AND COUNT(DISTINCT transaction_id) > 2

SELECT DISTINCT customer_id, COUNT(DISTINCT transaction_id) as transaction_count
FROM my_table
WHERE shop_name IN ('A','B')
AND transaction_date > 'yyyy-mm-dd'
AND COUNT(DISTINCT transaction_id) > 2

我有100张唱片

如果我写：

SELECT DISTINCT customer_id, COUNT(DISTINCT transaction_id) as transaction_count
FROM my_table
WHERE shop_name = 'A'
OR shop_name = 'B'
AND transaction_date > 'yyyy-mm-dd'
AND COUNT(DISTINCT transaction_id) > 2

SELECT DISTINCT customer_id, COUNT(DISTINCT transaction_id) as transaction_count
FROM my_table
WHERE shop_name IN ('A','B')
AND transaction_date > 'yyyy-mm-dd'
AND COUNT(DISTINCT transaction_id) > 2

我有50张唱片

为什么在这种情况下记录会有所不同？IN（商店名称）是否比IN（商店名称）更准确

---

谢谢。

如果您需要与运算符中的

或条件

相同的结果，则需要将

或条件

放在括号内-

SELECT DISTINCT customer_id, COUNT(DISTINCT transaction_id) as transaction_count
FROM my_table
WHERE (shop_name = 'A'
OR shop_name = 'B')
AND transaction_date > 'yyyy-mm-dd'
AND COUNT(DISTINCT transaction_id) > 2

询问

SELECT DISTINCT customer_id, COUNT(DISTINCT transaction_id) as transaction_count
FROM my_table
WHERE shop_name = 'A'
OR shop_name = 'B'
AND transaction_date > 'yyyy-mm-dd'
AND COUNT(DISTINCT transaction_id) > 2

相当于：

SELECT DISTINCT customer_id, COUNT(DISTINCT transaction_id) as transaction_count
FROM my_table
WHERE shop_name = 'A'
OR (shop_name = 'B'
    AND transaction_date > 'yyyy-mm-dd'
    AND COUNT(DISTINCT transaction_id) > 2)

---

这里附加的条件只影响shop_name='B'

查询缺少

GROUP BY

子句，或者它不是MS SQL Server（最终会出错）。谢谢@Fahmi，但是当我不添加括号时，它在做什么，结果似乎还是准确的？@nleiserowitz，应该是相同的结果-会有所不同。幸运的是，在这种情况下，您得到的是-但并非所有情况下都是一样的。