sql-server-2008 - SQL Server : Split operation

Question

如何在 SQL Server 中拆分字符串。

示例:

输入字符串:堆栈溢出

结果:

stack
over
flow

Answer 1

如果无法使用表值参数，请参阅:"Arrays and Lists in SQL Server 2008 Using Table-Valued Parameters" by Erland Sommarskog ，那么SQL Server中有很多种分割字符串的方法。本文涵盖了几乎每种方法的优点和缺点:

"Arrays and Lists in SQL Server 2005 and Beyond, When Table Value Parameters Do Not Cut it" by Erland Sommarskog

您需要创建一个分割函数。这是 split 函数的使用方式:

SELECT
    *
    FROM YourTable                               y
    INNER JOIN dbo.yourSplitFunction(@Parameter) s ON y.ID=s.Value

I prefer the number table approach to split a string in TSQL但是 SQL Server 中有多种分割字符串的方法，请参阅前面的链接，其中解释了每种方法的优点和缺点。

要使数字表方法发挥作用，您需要执行一次时间表设置，这将创建一个包含从 1 到 10,000 行的数字表:

SELECT TOP 10000 IDENTITY(int,1,1) AS Number
    INTO Numbers
    FROM sys.objects s1
    CROSS JOIN sys.objects s2
ALTER TABLE Numbers ADD CONSTRAINT PK_Numbers PRIMARY KEY CLUSTERED (Number)

设置 Numbers 表后，创建此拆分函数:

CREATE FUNCTION [dbo].[FN_ListToTable]
(
     @SplitOn  char(1)      --REQUIRED, the character to split the @List string on
    ,@List     varchar(8000)--REQUIRED, the list to split apart
)
RETURNS TABLE
AS
RETURN 
(

    ----------------
    --SINGLE QUERY-- --this will not return empty rows
    ----------------
    SELECT
        ListValue
        FROM (SELECT
                  LTRIM(RTRIM(SUBSTRING(List2, number+1, CHARINDEX(@SplitOn, List2, number+1)-number - 1))) AS ListValue
                  FROM (
                           SELECT @SplitOn + @List + @SplitOn AS List2
                       ) AS dt
                      INNER JOIN Numbers n ON n.Number < LEN(dt.List2)
                  WHERE SUBSTRING(List2, number, 1) = @SplitOn
             ) dt2
        WHERE ListValue IS NOT NULL AND ListValue!=''

);
GO 

您现在可以轻松地将 CSV 字符串拆分到表中并加入其中:

select * from dbo.FN_ListToTable(' ','stack over flow')

输出:

ListValue
-------------------
stack
over
flow

(3 row(s) affected)