How to select column used in parameter in sql

Question

Hi,
I have one View in which I am calling Function,
Below is the part of that Function. I am passing @Column_Name as parameter. I have total 3 Columns which I am using in my view form this function.
Now I have one issue in this SQL Query, instead of taking values from 'Alle' (or 'MeAlle', 'CurrentMe')column, my select statement is taking 'Alle' as value. I tried with Dynamic SQL but didn't work out for me.
Please help me on this below Query. Thanks in advance. 
DECLARE @Column_Name varchar(max)
SET @Column_Name = 'Alle' -- Alle, MeAlle, CurrentMe
DECLARE @TempAlleMes TABLE 
( PId int NOT NULL,
  Id nvarchar(max) NULL,
  Name nvarchar(max) NULL
INSERT INTO @TempAlleMes(PId,Id,Name)
SELECT p.PId,  
NullIf(SubString(',' + @Column_Name + ',' , t.ID , CharIndex(',' , ',' + @Column_Name + ',' , t.ID) - t.ID) , '') , ''  
FROM dbo.[Tally] t,[P_PsVs].dbo.[PInfo] p
WHERE t.ID <= Len(',' + @Column_Name + ',')
AND SubString(',' + @Column_Name + ',' , t.ID - 1, 1) = ','  
AND CharIndex(',' , ',' + @Column_Name + ',' , t.ID) - t.ID > 0 
and p.Pid = 302074
select * from @TempAlleMes
Vicky

Answer 1

This is a terrible table design.
Anyway, assuming you need to work with such design, you need to create fnSplit function in your database first. You can get any kind of implementation for such function, say, there is a blog by Jeff Moden that still has lots of discussion (I subscribed to
that discussion and get emails - too bad they only say there is a new reply instead of giving the reply):
http://www.sqlservercentral.com/articles/Tally+Table/72993/
So, once you have that splitting function in your database you can normalize your table using the following:
select T.*, F.Value, F.Id from myTable T CROSS APPLY dbo.fnSplit(T.Alle, ',') F
If you need to split several columns, then it will be a bit more complex as you would need to split each individual column separately using the above code and cte and then use the FULL JOIN based on main table PK and function's ID column to join the results.
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