我有一些数据,我想根据可能存在或不存在的分隔符进行拆分。
示例数据:
John/Smith
Jane/Doe
Steve
Bob/Johnson
我使用以下代码将此数据拆分为名字和姓氏:
SELECT SUBSTRING(myColumn, 1, CHARINDEX('/', myColumn)-1) AS FirstName,
SUBSTRING(myColumn, CHARINDEX('/', myColumn) + 1, 1000) AS LastName
FROM MyTable
结果我想:
FirstName---LastName
John--------Smith
Jane--------Doe
Steve-------NULL
Bob---------Johnson
只要所有行都具有预期的分隔符,此代码就可以正常工作,但是当行没有时出错:
"Invalid length parameter passed to the LEFT or SUBSTRING function."
如何重写这个才能正常工作?
可能这会对你有所帮助。
SELECT SUBSTRING(myColumn, 1, CASE CHARINDEX('/', myColumn)
WHEN 0
THEN LEN(myColumn)
ELSE CHARINDEX('/', myColumn) - 1
END) AS FirstName
,SUBSTRING(myColumn, CASE CHARINDEX('/', myColumn)
WHEN 0
THEN LEN(myColumn) + 1
ELSE CHARINDEX('/', myColumn) + 1
END, 1000) AS LastName
FROM MyTable
对于那些寻找SQL Server 2016+的答案的人。使用内置的STRING_SPLIT函数
例如:
DECLARE @tags NVARCHAR(400) = 'clothing,road,,touring,bike'
SELECT value
FROM STRING_SPLIT(@tags, ',')
WHERE RTRIM(value) <> '';
SELECT CASE WHEN CHARINDEX('/', myColumn, 0) = 0 THEN myColumn ELSE LEFT(myColumn, CHARINDEX('/', myColumn, 0)-1) END AS FirstName ,CASE WHEN CHARINDEX('/', myColumn, 0) = 0 THEN '' ELSE RIGHT(myColumn, CHARINDEX('/', REVERSE(myColumn), 0)-1) END AS LastName FROM MyTable
尝试使用分隔符过滤掉包含字符串的行,并仅处理以下内容:
SELECT SUBSTRING(myColumn, 1, CHARINDEX('/', myColumn)-1) AS FirstName,
SUBSTRING(myColumn, CHARINDEX('/', myColumn) + 1, 1000) AS LastName
FROM MyTable
WHERE CHARINDEX('/', myColumn) > 0
要么
SELECT SUBSTRING(myColumn, 1, CHARINDEX('/', myColumn)-1) AS FirstName,
SUBSTRING(myColumn, CHARINDEX('/', myColumn) + 1, 1000) AS LastName
FROM MyTable
WHERE myColumn LIKE '%/%'
我只想提供一种替代方法来分割带有多个分隔符的字符串,以防您在2016年使用SQL Server版本。
一般的想法是拆分字符串中的所有字符,确定分隔符的位置,然后获得相对于分隔符的子字符串。这是一个示例:
-- Sample data
DECLARE @testTable TABLE (
TestString VARCHAR(50)
)
INSERT INTO @testTable VALUES
('Teststring,1,2,3')
,('Test')
DECLARE @delimiter VARCHAR(1) = ','
-- Generate numbers with which we can enumerate
;WITH Numbers AS (
SELECT 1 AS N
UNION ALL
SELECT N + 1
FROM Numbers
WHERE N < 255
),
-- Enumerate letters in the string and select only the delimiters
Letters AS (
SELECT n.N
, SUBSTRING(t.TestString, n.N, 1) AS Letter
, t.TestString
, ROW_NUMBER() OVER ( PARTITION BY t.TestString
ORDER BY n.N
) AS Delimiter_Number
FROM Numbers n
INNER JOIN @testTable t
ON n <= LEN(t.TestString)
WHERE SUBSTRING(t.TestString, n, 1) = @delimiter
UNION
-- Include 0th position to "delimit" the start of the string
SELECT 0
, NULL
, t.TestString
, 0
FROM @testTable t
)
-- Obtain substrings based on delimiter positions
SELECT t.TestString
, ds.Delimiter_Number + 1 AS Position
, SUBSTRING(t.TestString, ds.N + 1, ISNULL(de.N, LEN(t.TestString) + 1) - ds.N - 1) AS Delimited_Substring
FROM @testTable t
LEFT JOIN Letters ds
ON t.TestString = ds.TestString
LEFT JOIN Letters de
ON t.TestString = de.TestString
AND ds.Delimiter_Number + 1 = de.Delimiter_Number
OPTION (MAXRECURSION 0)
当只有一个分隔符时,上面的示例工作正常,但对于多个分隔符,它不能很好地扩展。请注意,这仅适用于SQL Server 2016及更高版本。
/*Some Sample Data*/
DECLARE @mytable TABLE ([id] VARCHAR(10), [name] VARCHAR(1000));
INSERT INTO @mytable
VALUES ('1','John/Smith'),('2','Jane/Doe'), ('3','Steve'), ('4','Bob/Johnson')
/*Split based on delimeter*/
SELECT P.id, [1] 'FirstName', [2] 'LastName', [3] 'Col3', [4] 'Col4'
FROM(
SELECT A.id, X1.VALUE, ROW_NUMBER() OVER (PARTITION BY A.id ORDER BY A.id) RN
FROM @mytable A
CROSS APPLY STRING_SPLIT(A.name, '/') X1
) A
PIVOT (MAX(A.[VALUE]) FOR A.RN IN ([1],[2],[3],[4],[5])) P
ALTER FUNCTION [dbo].[split_string](
@delimited NVARCHAR(MAX),
@delimiter NVARCHAR(100)
) RETURNS @t TABLE (id INT IDENTITY(1,1), val NVARCHAR(MAX))
AS
BEGIN
DECLARE @xml XML
SET @xml = N'<t>' + REPLACE(@delimited,@delimiter,'</t><t>') + '</t>'
INSERT INTO @t(val)
SELECT r.value('.','varchar(MAX)') as item
FROM @xml.nodes('/t') as records(r)
RETURN
END