使用SQL Server,我如何分割一个字符串,以便我可以访问项目x?
拿一根“你好,约翰·史密斯”的绳子。我如何通过空格分割字符串并访问索引1应该返回“约翰”的项目?
使用SQL Server,我如何分割一个字符串,以便我可以访问项目x?
拿一根“你好,约翰·史密斯”的绳子。我如何通过空格分割字符串并访问索引1应该返回“约翰”的项目?
当前回答
在这里我发布了一个简单的解决方法
CREATE FUNCTION [dbo].[split](
@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
像这样执行函数
select * from dbo.split('Hello John Smith',' ')
其他回答
在Azure SQL数据库(基于Microsoft SQL Server但不完全相同的东西)中,STRING_SPLIT函数的签名看起来像这样:
STRING_SPLIT ( string , separator [ , enable_ordinal ] )
当enable_ordinal标志设置为1时,结果将包括一个名为ordinal的列,该列由输入字符串中子字符串的基于1的位置组成:
SELECT *
FROM STRING_SPLIT('hello john smith', ' ', 1)
| value | ordinal |
|-------|---------|
| hello | 1 |
| john | 2 |
| smith | 3 |
这允许我们这样做:
SELECT value
FROM STRING_SPLIT('hello john smith', ' ', 1)
WHERE ordinal = 2
| value |
|-------|
| john |
如果enable_ordinal不可用,则有一个技巧,即假定输入字符串中的子字符串是惟一的。在这种情况下,CHAR_INDEX可以用来查找子字符串在输入字符串中的位置:
SELECT value, ROW_NUMBER() OVER (ORDER BY CHARINDEX(value, input_str)) AS ord_pos
FROM (VALUES
('hello john smith')
) AS x(input_str)
CROSS APPLY STRING_SPLIT(input_str, ' ')
| value | ord_pos |
|-------+---------|
| hello | 1 |
| john | 2 |
| smith | 3 |
Alter Function dbo.fn_Split
(
@Expression nvarchar(max),
@Delimiter nvarchar(20) = ',',
@Qualifier char(1) = Null
)
RETURNS @Results TABLE (id int IDENTITY(1,1), value nvarchar(max))
AS
BEGIN
/* USAGE
Select * From dbo.fn_Split('apple pear grape banana orange honeydew cantalope 3 2 1 4', ' ', Null)
Select * From dbo.fn_Split('1,abc,"Doe, John",4', ',', '"')
Select * From dbo.fn_Split('Hello 0,"&""&&&&', ',', '"')
*/
-- Declare Variables
DECLARE
@X xml,
@Temp nvarchar(max),
@Temp2 nvarchar(max),
@Start int,
@End int
-- HTML Encode @Expression
Select @Expression = (Select @Expression For XML Path(''))
-- Find all occurences of @Delimiter within @Qualifier and replace with |||***|||
While PATINDEX('%' + @Qualifier + '%', @Expression) > 0 AND Len(IsNull(@Qualifier, '')) > 0
BEGIN
Select
-- Starting character position of @Qualifier
@Start = PATINDEX('%' + @Qualifier + '%', @Expression),
-- @Expression starting at the @Start position
@Temp = SubString(@Expression, @Start + 1, LEN(@Expression)-@Start+1),
-- Next position of @Qualifier within @Expression
@End = PATINDEX('%' + @Qualifier + '%', @Temp) - 1,
-- The part of Expression found between the @Qualifiers
@Temp2 = Case When @End < 0 Then @Temp Else Left(@Temp, @End) End,
-- New @Expression
@Expression = REPLACE(@Expression,
@Qualifier + @Temp2 + Case When @End < 0 Then '' Else @Qualifier End,
Replace(@Temp2, @Delimiter, '|||***|||')
)
END
-- Replace all occurences of @Delimiter within @Expression with '</fn_Split><fn_Split>'
-- And convert it to XML so we can select from it
SET
@X = Cast('<fn_Split>' +
Replace(@Expression, @Delimiter, '</fn_Split><fn_Split>') +
'</fn_Split>' as xml)
-- Insert into our returnable table replacing '|||***|||' back to @Delimiter
INSERT @Results
SELECT
"Value" = LTRIM(RTrim(Replace(C.value('.', 'nvarchar(max)'), '|||***|||', @Delimiter)))
FROM
@X.nodes('fn_Split') as X(C)
-- Return our temp table
RETURN
END
我使用弗雷德里克的答案,但这在SQL Server 2005中不起作用
我修改了它,我使用select with union all,它可以工作
DECLARE @str varchar(max)
SET @str = 'Hello John Smith how are you'
DECLARE @separator varchar(max)
SET @separator = ' '
DECLARE @Splited table(id int IDENTITY(1,1), item varchar(max))
SET @str = REPLACE(@str, @separator, ''' UNION ALL SELECT ''')
SET @str = ' SELECT ''' + @str + ''' '
INSERT INTO @Splited
EXEC(@str)
SELECT * FROM @Splited
结果集是:
id item
1 Hello
2 John
3 Smith
4 how
5 are
6 you
如果数据库的兼容性级别为130或更高,则可以使用STRING_SPLIT函数和OFFSET FETCH子句按索引获取特定的项。
要获得索引N(从零开始)的项,可以使用以下代码
SELECT value
FROM STRING_SPLIT('Hello John Smith',' ')
ORDER BY (SELECT NULL)
OFFSET N ROWS
FETCH NEXT 1 ROWS ONLY
要检查数据库的兼容性级别,执行以下代码:
SELECT compatibility_level
FROM sys.databases WHERE name = 'YourDBName';
下面的示例使用递归CTE
更新18.09.2013
CREATE FUNCTION dbo.SplitStrings_CTE(@List nvarchar(max), @Delimiter nvarchar(1))
RETURNS @returns TABLE (val nvarchar(max), [level] int, PRIMARY KEY CLUSTERED([level]))
AS
BEGIN
;WITH cte AS
(
SELECT SUBSTRING(@List, 0, CHARINDEX(@Delimiter, @List + @Delimiter)) AS val,
CAST(STUFF(@List + @Delimiter, 1, CHARINDEX(@Delimiter, @List + @Delimiter), '') AS nvarchar(max)) AS stval,
1 AS [level]
UNION ALL
SELECT SUBSTRING(stval, 0, CHARINDEX(@Delimiter, stval)),
CAST(STUFF(stval, 1, CHARINDEX(@Delimiter, stval), '') AS nvarchar(max)),
[level] + 1
FROM cte
WHERE stval != ''
)
INSERT @returns
SELECT REPLACE(val, ' ','' ) AS val, [level]
FROM cte
WHERE val > ''
RETURN
END
演示SQLFiddle