Sql 将返回的字符串拆分为多个列

我有一个字符串，其中包含由“/”字符分隔的项目层次结构

例如：类\目\科\属\种

我需要拆分这个字符串，这样每个值都是它自己的列，并且显示原始的完整字符串

例如

变成

Classification Class Order Family  Genus Species  
-------------- ----- ----- ------  ----- -------
Mammalia\Carnivora\Felidae\Panthera\tigris Mammalia  Carnivora Felidae Pathera tigris  
Mammalia\Carnivora\Felidae\Panthera\leo Mammalia  Carnivora Felidae Pathera leo  
Mammalia\Carnivora\Felidae\Panthera\pardus  Mammalia  Carnivora Felidae Pathera pardus  

Classification Class Order Family  Genus Species  
Mammalia\Carnivora\Felidae Mammalia  Carnivora Felidae NULL NULL

最后，并非所有字符串都有5个值，因此脚本需要 为不存在的值输入NULL

例如

变成

Classification Class Order Family  Genus Species  
-------------- ----- ----- ------  ----- -------
Mammalia\Carnivora\Felidae\Panthera\tigris Mammalia  Carnivora Felidae Pathera tigris  
Mammalia\Carnivora\Felidae\Panthera\leo Mammalia  Carnivora Felidae Pathera leo  
Mammalia\Carnivora\Felidae\Panthera\pardus  Mammalia  Carnivora Felidae Pathera pardus  

Classification Class Order Family  Genus Species  
Mammalia\Carnivora\Felidae Mammalia  Carnivora Felidae NULL NULL

---

这应该是你想要的

它使用公共表表达式将字符串拆分为部分级别。请注意，我不需要添加\来正确拆分它，这样输入字符串的末尾就不应该有\了

然后，您只需获得每个级别的值

DECLARE @string NVARCHAR(500) = 'Mammalia\Carnivora\Felidae\Panthera\Panthera tigris'

;WITH cte
AS
(
    SELECT SUBSTRING(@string + '\', 1, CHARINDEX('\', @string, 1) - 1) AS Part, 
        SUBSTRING(@string + '\', CHARINDEX('\', @string, 1) + 1, LEN(@string + '\') - CHARINDEX('\', @string, 1) + 1) AS Remainder,
        0 AS Level

    UNION ALL

    SELECT SUBSTRING(cte.Remainder, 1, CHARINDEX('\', cte.Remainder, 1) - 1) AS Part, 
        SUBSTRING(cte.Remainder, CHARINDEX('\', cte.Remainder, 1) + 1, LEN(cte.Remainder) - CHARINDEX('\', cte.Remainder, 1) + 1) AS Remainder,
        cte.Level + 1 AS Level
    FROM cte
    WHERE CHARINDEX('\', cte.Remainder, 1) > 0
)

SELECT
    @string Classification,
    (SELECT Part FROM cte WHERE Level = 0) Class,
    (SELECT Part FROM cte WHERE Level = 1) [Order],
    (SELECT Part FROM cte WHERE Level = 2) Family,
    (SELECT Part FROM cte WHERE Level = 3) Genus,
    (SELECT Part FROM cte WHERE Level = 4) Species