How to Split a string by delimited char in SQL Server

CREATE FUNCTION [dbo].[fnSplitString] 
( 
    @string NVARCHAR(MAX), 
    @delimiter CHAR(1) 
) 
RETURNS @output TABLE(splitdata NVARCHAR(MAX) 
) 
BEGIN 
    DECLARE @start INT, @end INT 
    SELECT @start = 1, @end = CHARINDEX(@delimiter, @string) 
    WHILE @start < LEN(@string) + 1 BEGIN 
        IF @end = 0  
            SET @end = LEN(@string) + 1
       
        INSERT INTO @output (splitdata)  
        VALUES(SUBSTRING(@string, @start, @end - @start)) 
        SET @start = @end + 1 
        SET @end = CHARINDEX(@delimiter, @string, @start)
        
    END 
    RETURN 
END

select *from dbo.fnSplitString('Querying SQL Server','')

Character arrays in T-SQL

--Inputs
declare @x varchar(100)
set @x = 'WORDS'

--Table of letters (like an array)
select substring(@x, number, 1) as v
from master.dbo.spt_values where number between 1 and len(@x) group by number order by number

--Example manipulation
declare @y varchar(100)
select @y = isnull(@y, '') + char(ascii(substring(@x, number, 1))+1)
from master.dbo.spt_values where number between 1 and len(@x) group by number order by number

select @x as 'Original', @y as 'Manipulated (shifted by 1)'
/*Results
v   
----
W
O
R
D
S

Original         Manipulated (shifted by 1)  
---------------- -----------------------------
WORDS            XPSET
*/