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

CREATE TABLE test(
    id int,
    adress varchar(100)
);
INSERT INTO test VALUES(1, 'Ludovic Aubert, 42 rue de la Victoire, 75009, Paris, France'),(2, 'Jose Garcia, 1 Calle de la Victoria, 56500 Barcelona, Espana');

SELECT id, value, COUNT(*) OVER (PARTITION BY id) AS n, ROW_NUMBER() OVER (PARTITION BY id ORDER BY (SELECT NULL)) AS rn, adress
FROM test
CROSS APPLY STRING_SPLIT(adress, ',')

其他回答

递归CTE解决方案与服务器疼痛,测试它

MS SQL Server 2008模式设置:

create table Course( Courses varchar(100) );
insert into Course values ('Hello John Smith');

查询1:

with cte as
   ( select 
        left( Courses, charindex( ' ' , Courses) ) as a_l,
        cast( substring( Courses, 
                         charindex( ' ' , Courses) + 1 , 
                         len(Courses ) ) + ' ' 
              as varchar(100) )  as a_r,
        Courses as a,
        0 as n
     from Course t
    union all
      select 
        left(a_r, charindex( ' ' , a_r) ) as a_l,
        substring( a_r, charindex( ' ' , a_r) + 1 , len(a_R ) ) as a_r,
        cte.a,
        cte.n + 1 as n
    from Course t inner join cte 
         on t.Courses = cte.a and len( a_r ) > 0

   )
select a_l, n from cte
--where N = 1

结果:

|    A_L | N |
|--------|---|
| Hello  | 0 |
|  John  | 1 |
| Smith  | 2 |

你可以在SQL用户定义函数解析带分隔符的字符串中找到有用的解决方案(来自代码项目)。

你可以使用这个简单的逻辑:

Declare @products varchar(200) = '1|20|3|343|44|6|8765'
Declare @individual varchar(20) = null

WHILE LEN(@products) > 0
BEGIN
    IF PATINDEX('%|%', @products) > 0
    BEGIN
        SET @individual = SUBSTRING(@products,
                                    0,
                                    PATINDEX('%|%', @products))
        SELECT @individual

        SET @products = SUBSTRING(@products,
                                  LEN(@individual + '|') + 1,
                                  LEN(@products))
    END
    ELSE
    BEGIN
        SET @individual = @products
        SET @products = NULL
        SELECT @individual
    END
END

你可以在SQL中拆分字符串,而不需要函数:

DECLARE @bla varchar(MAX)
SET @bla = 'BED40DFC-F468-46DD-8017-00EF2FA3E4A4,64B59FC5-3F4D-4B0E-9A48-01F3D4F220B0,A611A108-97CA-42F3-A2E1-057165339719,E72D95EA-578F-45FC-88E5-075F66FD726C'

-- http://stackoverflow.com/questions/14712864/how-to-query-values-from-xml-nodes
SELECT 
    x.XmlCol.value('.', 'varchar(36)') AS val 
FROM 
(
    SELECT 
    CAST('<e>' + REPLACE(@bla, ',', '</e><e>') + '</e>' AS xml) AS RawXml
) AS b 
CROSS APPLY b.RawXml.nodes('e') x(XmlCol);

如果需要支持任意字符串(带有xml特殊字符)

DECLARE @bla NVARCHAR(MAX)
SET @bla = '<html>unsafe & safe Utf8CharsDon''tGetEncoded ÄöÜ - "Conex"<html>,Barnes & Noble,abc,def,ghi'

-- http://stackoverflow.com/questions/14712864/how-to-query-values-from-xml-nodes
SELECT 
    x.XmlCol.value('.', 'nvarchar(MAX)') AS val 
FROM 
(
    SELECT 
    CAST('<e>' + REPLACE((SELECT @bla FOR XML PATH('')), ',', '</e><e>') + '</e>' AS xml) AS RawXml
) AS b 
CROSS APPLY b.RawXml.nodes('e') x(XmlCol); 

下面是一个函数,它将完成问题的目标,即分割字符串并访问项目X:

CREATE FUNCTION [dbo].[SplitString]
(
   @List       VARCHAR(MAX),
   @Delimiter  VARCHAR(255),
   @ElementNumber INT
)
RETURNS VARCHAR(MAX)
AS
BEGIN

       DECLARE @inp VARCHAR(MAX)
       SET @inp = (SELECT REPLACE(@List,@Delimiter,'_DELMTR_') FOR XML PATH(''))

       DECLARE @xml XML
       SET @xml = '<split><el>' + REPLACE(@inp,'_DELMTR_','</el><el>') + '</el></split>'

       DECLARE @ret VARCHAR(MAX)
       SET @ret = (SELECT
              el = split.el.value('.','varchar(max)')
       FROM  @xml.nodes('/split/el[string-length(.)>0][position() = sql:variable("@elementnumber")]') split(el))

       RETURN @ret

END

用法:

SELECT dbo.SplitString('Hello John Smith', ' ', 2)

结果:

John

从SQL Server 2016开始,我们使用string_split

DECLARE @string varchar(100) = 'Richard, Mike, Mark'

SELECT value FROM string_split(@string, ',')