[sql] 切開同一欄位用逗點隔開的資訊

遇到一個狀況，資料庫顯示為

| CODE |   FK    |
-----------------------
|  A  |   1,2,3 |

我需要轉如下才能關聯....

| CODE |  FK   |
-----------------------
|  A  |     1 |
|  A  |     2 |
|  A  |     3 |

解法 :
參考 : https://stackoverflow.com/questions/13527537/sql-query-to-split-column-data-into-rows

先建立sql function

create FUNCTION [dbo].[Split](@String varchar(MAX), @Delimiter char(1))       
returns @temptable TABLE (items varchar(MAX))       
as       
begin      
    declare @idx int       
    declare @slice varchar(8000)       

    select @idx = 1       
        if len(@String)<1 or @String is null  return       

    while @idx!= 0       
    begin       
        set @idx = charindex(@Delimiter,@String)       
        if @idx!=0       
            set @slice = left(@String,@idx - 1)       
        else       
            set @slice = @String       

        if(len(@slice)>0)  
            insert into @temptable(Items) values(@slice)       

        set @String = right(@String,len(@String) - @idx)       
        if len(@String) = 0 break       
    end   
return 
end;

然後下以下sql 句即可
select t1.Code, s.items FK
from [table] t1
outer apply dbo.Split(t1.FK, ',') s

outer apply : 說明參考 https://ithelp.ithome.com.tw/articles/10195219