DECLARE @FP VARCHAR(3)
DECLARE @FP1 VARCHAR(1)
DECLARE @FP2 VARCHAR(1)
SET @FP = 'AAA'
SET @FP1 = SUBSTRING(@FP,LEN(@FP)-1,1)
SET @FP2 = SUBSTRING(@FP,LEN(@FP),1)
SELECT @FP, @FP1, ASCII(@FP1), @FP2, ASCII(@FP2)


IF(ASCII(@FP2)=90)
BEGIN
SET @FP2='A' 
SET @FP1=CHAR(ASCII(@FP1)+1)
IF(ASCII(@FP1)>90)
BEGIN
SET @FP1='A'
SET @FP='A'+@FP1+@FP2
END
ELSE
BEGIN
SET @FP=@FP1+@FP2
END
END
ELSE IF(ASCII(@FP2)<90)
BEGIN
SET @FP2=CHAR(ASCII(@FP2)+1)
SET @FP=@FP1+@FP2
END


SELECT @FP, @FP1, ASCII(@FP1), @FP2, ASCII(@FP2)

declare @test varchar(4)
set @test = 'AAZ'

-- See Jeff Modem's article The "Numbers" or "Tally" Table: What it is and how it replaces a loop.
-- at http://www.sqlservercentral.com/articles/T-SQL/62867/.
;WITH 
Tens     (N) AS (SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0 UNION ALL 
                 SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0 UNION ALL 
                 SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0), 
Thousands(N) AS (SELECT 1 FROM Tens t1 CROSS JOIN Tens t2 CROSS JOIN Tens t3), 
Millions (N) AS (SELECT 1 FROM Thousands t1 CROSS JOIN Thousands t2), 
Tally    (N) AS (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM Millions),
CTE1     (A) AS (SELECT CHAR(N+64) FROM Tally WHERE N between 1 and 26),
CTE2     (B) AS (SELECT c1.A + c2.A FROM CTE1 c1 CROSS JOIN CTE1 c2),
CTE3     (C) AS (SELECT c1.A + c2.A + c3.A FROM CTE1 c1 CROSS JOIN CTE1 c2 CROSS JOIN CTE1 c3),
CTE4     (D) AS (SELECT c1.A + c2.A + c3.A + c4.A FROM CTE1 c1 CROSS JOIN CTE1 c2 CROSS JOIN CTE1 c3 CROSS JOIN CTE1 c4),
CTE          AS (SELECT A, RN = 1 FROM CTE1 UNION ALL
                 SELECT B, RN = 2  FROM CTE2 UNION ALL
                 SELECT C, RN = 3  FROM CTE3 UNION ALL
                 SELECT D, RN = 4 FROM CTE4)
SELECT TOP 1 A FROM CTE WHERE A > @test and RN >= LEN(@test)

;WITH TALLY AS
(	
           SELECT 1 N
 UNION ALL SELECT 2
 UNION ALL SELECT 3
 UNION ALL SELECT 4
 UNION ALL SELECT 5
 UNION ALL SELECT 6
 UNION ALL SELECT 7
 UNION ALL SELECT 8
 UNION ALL SELECT 9
 UNION ALL SELECT 10
 UNION ALL SELECT 11
 UNION ALL SELECT 12
 UNION ALL SELECT 13
 UNION ALL SELECT 14
 UNION ALL SELECT 15
 UNION ALL SELECT 16
 UNION ALL SELECT 17
 UNION ALL SELECT 18
 UNION ALL SELECT 19
 UNION ALL SELECT 20
 UNION ALL SELECT 21
 UNION ALL SELECT 22
 UNION ALL SELECT 23
 UNION ALL SELECT 24
 UNION ALL SELECT 25
 UNION ALL SELECT 26
),
DEUX AS
(
  SELECT T1.N	C1 , T2.N  C2 FROM TALLY T1 CROSS JOIN TALLY T2
),
TROIS AS
(
  SELECT T1. C1  , T1.C2  C2, T2.N C3 FROM DEUX T1 CROSS JOIN TALLY T2
),
QUATRE AS
(
  SELECT T1. C1  , T1.C2  C2, T1.C3 C3 , T2.N C4 FROM TROIS T1 CROSS JOIN TALLY T2
)
SELECT CHAR(64 + N) ALPHA  FROM TALLY
UNION ALL
SELECT CHAR(64 + C2) + CHAR(64 + C1)   FROM DEUX
UNION ALL
SELECT CHAR(64 + C3)+  CHAR(64 + C2) + CHAR(64 + C1)  FROM TROIS
UNION ALL
SELECT CHAR(64 + C4)+  CHAR(64 + C3)+  CHAR(64 + C2) + CHAR(64 + C1)  FROM QUATRE

	Me		wayne	
	cpu	elapsed	cpu 	elapsed
1	391	387	672	376
2	375	389	671	693
3	390	402	672	673
4	391	388	703	690
5	391	386	671	672
Result	387.6	390.4	677.8	620.8

;WITH 
/* 
--Am commenting this section of the code which is taking that extra time

Tens     (N) AS (SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0 UNION ALL 
                 SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0 UNION ALL 
                 SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0), 
Thousands(N) AS (SELECT 1 FROM Tens t1 CROSS JOIN Tens t2 CROSS JOIN Tens t3), 
Millions (N) AS (SELECT 1 FROM Thousands t1 CROSS JOIN Thousands t2), 
Tally    (N) AS (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM Millions),*/
;WITH TALLY AS
(	
           SELECT 1 N
 UNION ALL SELECT 2
 UNION ALL SELECT 3
 UNION ALL SELECT 4
 UNION ALL SELECT 5
 UNION ALL SELECT 6
 UNION ALL SELECT 7
 UNION ALL SELECT 8
 UNION ALL SELECT 9
 UNION ALL SELECT 10
 UNION ALL SELECT 11
 UNION ALL SELECT 12
 UNION ALL SELECT 13
 UNION ALL SELECT 14
 UNION ALL SELECT 15
 UNION ALL SELECT 16
 UNION ALL SELECT 17
 UNION ALL SELECT 18
 UNION ALL SELECT 19
 UNION ALL SELECT 20
 UNION ALL SELECT 21
 UNION ALL SELECT 22
 UNION ALL SELECT 23
 UNION ALL SELECT 24
 UNION ALL SELECT 25
 UNION ALL SELECT 26
),
CTE1     (A) AS (SELECT CHAR(N+64) FROM Tally WHERE N between 1 and 26),
CTE2     (B) AS (SELECT c1.A + c2.A FROM CTE1 c1 CROSS JOIN CTE1 c2),
CTE3     (C) AS (SELECT c1.A + c2.A + c3.A FROM CTE1 c1 CROSS JOIN CTE1 c2 CROSS JOIN CTE1 c3),
CTE4     (D) AS (SELECT c1.A + c2.A + c3.A + c4.A FROM CTE1 c1 CROSS JOIN CTE1 c2 CROSS JOIN CTE1 c3 CROSS JOIN CTE1 c4),
CTE          AS (SELECT A, RN = 1 FROM CTE1 UNION ALL
                 SELECT B, RN = 2  FROM CTE2 UNION ALL
                 SELECT C, RN = 3  FROM CTE3  UNION ALL
                 SELECT D, RN = 4 FROM CTE4 )
SELECT   A  FROM CTE