SQL 中的 IsDate 函数将无效日期评估为有效 [英] IsDate Function in SQL evaluates invalid dates as valid

问题描述

我正在针对从 Excel 文件导入的数据运行 SQL 语句.在此 SQL 中，我正在检查用户是否使用 IsDate 函数正确输入了日期.由于这是尚未转换的原始数据，因此所有日期都存储在 varchar 数据类型字段中.

I am running a SQL Statement against imported data from Excel Files. In this SQL I am checking if the users have entered dates properly by using IsDate function. Since this is a raw data that hasn't been converted yet, all dates are stored in a varchar data type field.

在某些情况下，当用户输入的日期格式明显不正确时，IsDate 会返回 1(有效日期).

In some circumstances IsDate returns 1 (valid date) when there is clearly an incorrect date format entered by the user.

例如:

07/001/2012

2012-07-002

007/002/2012

关于如何处理这个问题有什么建议吗?

Any Suggestions on how to handle this problem?

SELECT *
  FROM tblImport
 WHERE (ISDATE(dt) = 0 
        AND (dt is not null AND dt <> ''))

谢谢！

附言殴打用户没有帮助.

p.s. Smacking users' did not help.

推荐答案

我做了很多数据转换工作，这是我创建的一个函数，我几乎每天都使用它来清除错误日期:

I do a lot of data conversion work and here is a function that I created and use it practically everyday to weed out the bad dates:

CREATE FUNCTION dbo.fnCheckDate
(@InDate nvarchar(50))
RETURNS DATETIME
AS
    BEGIN
        declare @Return DATETIME

        select @return = CASE WHEN ISDATE(@InDate) = 1
                            THEN CASE WHEN CAST(@InDate as DATETIME) BETWEEN '1/1/1901 12:00:00 AM' AND '6/6/2079 12:00:00 AM'
                                    THEN @InDate
                                    ELSE null
                                    END
                            ELSE null
                            END
        return @return
    END
GO

结果:

SELECT dbo.fnCheckDate('07/001/2012') --> Returns 2012-07-01 00:00:00.000
SELECT dbo.fnCheckDate('2012-07-002') --> Returns 2012-07-01 00:00:00.000
SELECT dbo.fnCheckDate('007/002/2012') --> Returns 2012-07-01 00:00:00.000
SELECT dbo.fnCheckDate('00/002/2012') --> Returns Null
SELECT dbo.fnCheckDate('006/031/2012') --> Returns Null
SELECT dbo.fnCheckDate('') --> Returns Null

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