sql - CASE 的“子查询返回超过 1 个值”错误

Question

表结构：

Customer
    ID int not null,
    Name varchar(100) null

询问：

SELECT ID, 
  (SELECT CASE WHEN (Name IS NULL AND Name <> '')
          THEN CAST(1 AS BIT)
          ELSE CAST(0 AS BIT) END
   FROM Customer) AS IsNameNullOrWhitespace

这给了我“子查询返回超过 1 个值这是 ..”。为什么是这样？

Answer 1

看来您不需要子查询-您可以将 嵌入case到顶级 中select，如下所示：

SELECT id, 
       CASE 
         WHEN ( name IS NULL 
                AND name <> '' ) THEN Cast(1 AS BIT) 
         ELSE Cast(0 AS BIT) 
       END AS IsNameNullOrWhitespace 
FROM   customer 

Answer 2

SELECT ID, 
Case When IsNull(Name,'') ='' Then CAST(1 AS BIT) Else CAST(0 AS BIT) End  
IsNameNullOrWhitespace
FROM Customer

您需要以上查询。