在SQL Server中从CSV列创建表，而不使用游标 [英] Create a table from CSV columns in SQL Server without using a cursor

问题描述

给出一个表：

|Name    | Hobbies                |
-----------------------------------
|Joe     | Eating,Running,Golf    |
|Dafydd  | Swimming,Coding,Gaming |

我想将这些行拆分为：

|Name    | Hobby     |
----------------------
|Joe     | Eating    |
|Joe     | Running   |
|Joe     | Golf      |
|Dafydd  | Swimming  |
|Dafydd  | Coding    |
|Dafydd  | Gaming    |

我已经完成了下面的例子（例子已准备好在SSMS中运行），购买我的解决方案使用一个光标我认为是丑陋的。有没有更好的方法这样做？

I have completed this below (example is ready to run in SSMS), buy my solution uses a cursor which I think is ugly. Is there a better way of doing this? I am on SQL Server 2008 R2 if there is anything new which will help me.

感谢

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[Split]') and xtype in (N'FN', N'IF', N'TF')) drop function [dbo].Split
go
CREATE FUNCTION dbo.Split (@sep char(1), @s varchar(512))
RETURNS table
AS
RETURN (
    WITH Pieces(pn, start, stop) AS (
      SELECT 1, 1, CHARINDEX(@sep, @s)
      UNION ALL
      SELECT pn + 1, stop + 1, CHARINDEX(@sep, @s, stop + 1)
      FROM Pieces
      WHERE stop > 0
    )
    SELECT pn,
      SUBSTRING(@s, start, CASE WHEN stop > 0 THEN stop-start ELSE 512 END) AS s
    FROM Pieces
  )


go

declare @inputtable table (
    name varchar(200) not null,
    hobbies varchar(200) not null
)

declare @outputtable table (
    name varchar(200) not null,
    hobby varchar(200) not null
)

insert into @inputtable values('Joe', 'Eating,Running,Golf')
insert into @inputtable values('Dafydd', 'Swimming,Coding,Gaming')

select * from @inputtable

declare inputcursor cursor for
select name, hobbies
from @inputtable

open inputcursor

declare @name varchar(255), @hobbiescsv varchar(255)
fetch next from inputcursor into @name, @hobbiescsv
while(@@FETCH_STATUS <> -1) begin

    insert into @outputtable
    select @name, splithobbies.s
    from dbo.split(',', @hobbiescsv) splithobbies

    fetch next from inputcursor into @name, @hobbiescsv 
end
close inputcursor
deallocate inputcursor

select * from @outputtable

推荐答案

使用字符串解析函数，如此处。关键是使用 CROSS APPLY 为基表中的每一行执行函数。

Use a string parsing function like the one found here. The key is to use CROSS APPLY to execute the function for each row in your base table.

CREATE FUNCTION [dbo].[fnParseStringTSQL] (@string NVARCHAR(MAX),@separator NCHAR(1))
RETURNS @parsedString TABLE (string NVARCHAR(MAX))
AS 
BEGIN
   DECLARE @position int
   SET @position = 1
   SET @string = @string + @separator
   WHILE charindex(@separator,@string,@position) <> 0
      BEGIN
         INSERT into @parsedString
         SELECT substring(@string, @position, charindex(@separator,@string,@position) - @position)
         SET @position = charindex(@separator,@string,@position) + 1
      END
     RETURN
END
go

declare @MyTable table (
    Name char(10),
    Hobbies varchar(100)
)

insert into @MyTable
    (Name, Hobbies)
    select 'Joe', 'Eating,Running,Golf'
    union all
    select 'Dafydd', 'Swimming,Coding,Gaming'

select t.Name, p.String
    from @mytable t
        cross apply dbo.fnParseStringTSQL(t.Hobbies, ',') p

DROP FUNCTION [dbo].[fnParseStringTSQL]

这篇关于在SQL Server中从CSV列创建表，而不使用游标的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！