Question

select  CASE when  (select distinct BR.BorrowerID from tblBorrow BR 
inner join tblWorker W on W.ContractorID=BR.BorrowerID 
inner join  tblBorrowWorker TWB on  TWB.WorkerID=W.WorkerID 
inner join tblBorrowWorkerAssign TBWA on TWB.BorrowWorkerAssignmentID=TBWA.BorrowWorkerAssignmentID where TWB.WorkerID=11276) then 'BR.BorrowerID'   else 'NotBorrowed' end as BorrowedStatus

这里实际上在'Then'条件我想要显示BorrowerID，这里子查询部分运行良好并返回ID，但是当我添加CASE语句时它给出一个错误 “在预期条件的上下文中指定的非布尔类型的表达式，接近'then'。”此查询是我存储过程的一部分。将是解决方案

Answer 1

CASE子句需要一个布尔条件。你能用Exists（）检查真实情况吗？尝试将exists（）用于内部select语句（从select distinct BR.BorrowerID from tblBorrow BR...开始）

Answer 2

如果您要从子查询中显示BR.BorrowerID的值而不是'BR.BorrowerID'字符串常量，则可以尝试以下操作（假设您已确保子查询返回的行数不超过一行）：

SELECT
  ISNULL(
    (
      SELECT DISTINCT CAST(BR.BorrowerID AS varchar(15))
      FROM tblBorrow BR 
      INNER JOIN tblWorker W ON W.ContractorID = BR.BorrowerID 
      INNER JOIN tblBorrowWorker TWB ON TWB.WorkerID = W.WorkerID 
      INNER JOIN tblBorrowWorkerAssign TBWA ON TWB.BorrowWorkerAssignmentID = TBWA.BorrowWorkerAssignmentID
      WHERE TWB.WorkerID=11276
    ),
    'NotBorrowed'
  )

另一方面，如果这是您帖子中的完整查询（不是较大查询的一部分），则以下也可能是一个选项：

SELECT DISTINCT ISNULL(CAST(BR.BorrowerID AS varchar(15)), 'NotBorrowed')
FROM
    (SELECT 1) x (x)
    LEFT JOIN
        tblBorrow BR 
        INNER JOIN tblWorker W ON W.ContractorID = BR.BorrowerID 
        INNER JOIN tblBorrowWorker TWB ON TWB.WorkerID = W.WorkerID 
        INNER JOIN tblBorrowWorkerAssign TBWA ON TWB.BorrowWorkerAssignmentID = TBWA.BorrowWorkerAssignmentID
    ON TWB.WorkerID = 11276

(SELECT 1) x (x)“表”仅用于确保在左连接的右侧没有返回任何行的情况下结果集不为空。

Sql Server查询中的案例条件冲突

2 个答案: