SQL Server子查詢返回多個值。當子查詢跟隨（字符）或子查詢用作表達式時，這是不允許的

Question

我試圖根據它們的出現更新一些字段。如果他們只發生一次，我正在更新一些狀態字段。

我當前的代碼如下：

UPDATE table1 
SET statusField = 1 
WHERE someID = (
       SELECT someID 
       FROM table1 
       GROUP BY someID HAVING COUNT(*) = 1 
       ) 

這將返回一個錯誤，如一個在標題：Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.

是否有任何其他，如容易閱讀/簡單，解決這個？

Answer 1

使用IN關鍵字，而不是等於運營商，像這樣：

UPDATE table1 
SET statusField = 1 
WHERE someID IN (
      SELECT someID 
      FROM table1 
      GROUP BY someID HAVING COUNT(*) = 1 
      ) 

使用=要求恰好1結果子查詢返回。 IN關鍵字在列表中工作。

Answer 2

試試這個

使用頂

UPDATE table1 
SET statusField = 1 
WHERE someID = (
       SELECT TOP 1 someID 
       FROM table1 
       GROUP BY someID HAVING COUNT(*) = 1 
       ) 

或者你可以使用IN條款

UPDATE table1 
SET statusField = 1 
WHERE someID IN (
       SELECT someID 
       FROM table1 
       GROUP BY someID HAVING COUNT(*) = 1 
       ) 

Answer 3

你應該加入你的表中的子查詢中。這是可能的「中」使用，但在你的情況我會用存在：

UPDATE table1 x 
SET statusField = 1 
WHERE exists (
       SELECT null 
       FROM table1 
       WHERE x.someID = someID 
       GROUP BY someID 
       HAVING COUNT(*) = 1 
       ) 

爲了更好的表現，我會用這個腳本，而不是（SQLSERVER-2008 +）：

;WITH x as 
(
SELECT rc = count() over (partition by someID), statusField 
FROM table1 
) 
UPDATE x 
SET statusField = 1 
WHERE rc = 1