SQL Server 2008 中 WHERE 子句中的 CASE 语句

Question

我想写一个CASE语句，根据@sFRomDate是否为空来查找两个日期之间的数据。鉴于以下查询不符合我的要求。请帮我找到合适的解决方案

SELECT 
    * 
FROM 
    tbl_emp_data 
WHERE
    CASE 
       WHEN @sFRomDate!='' 
          THEN SubmissionDate BETWEEN @sFRomDate AND DATEADD(DAY,1,@sToDate) 
       ELSE
          SubmissionDate = NULL
    END

Answer 1

这可能是您试图实现的逻辑。如果 @sFRomDate 为 NULL 或为空并且 SubmissionDate 也为 NULL 或为空，则将返回记录。否则，将检查 SubmissionDate 以确保它在您定义的范围内。

SELECT *
FROM tbl_emp_data
WHERE (COALESCE(@sFRomDate, '') = '' AND
       COALESCE(SubmissionDate, '') = '') OR
      (COALESCE(@sFRomDate, '') <> ''     AND
       COALESCE(SubmissionDate, '') <> '' AND
       SubmissionDate BETWEEN @sFRomDate AND DATEADD(DAY, 1, @sToDate))

Answer 2

如果我明白你想要什么，我认为如果你这样写会更容易遵循逻辑：

IF @sFromDate = ''
BEGIN
SELECT * FROM tbl_emp_data where SubmissionDate=null
END
ELSE
BEGIN
SELECT * FROM tbl_emp_data where SubmissionDate between @sFRomDate and DATEADD(DAY,1,@sToDate)
END

但正如@Tim Biegeleisen 所说，要小心空值，不仅是@sFromDate，还有@sToDate

SQL Server 2008 中 WHERE 子句中的 CASE 语句

CASE statement within WHERE clause in SQL Server 2008

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where-clause

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