I saw the range table creation script and think that we can create it with another twist by utilizing Izik-Ben-Gan "Sequential Number table function" without using loop.

Result expected

RangeStart RangeEnd

AA AB

AB AC

....

The final solution be like one line of query.

WITH

L0 AS (

SELECT CHAR(n) AS Alphabet FROM dbo.[fn_nums](90) WHERE n >=65)

SELECT

A.Alphabet + B.Alphabet AS RangeStart,

A.Alphabet + char(ascii(B.Alphabet)+1) AS RangeEnd

FROM L0 AS A, L0 AS B

WHERE

A.Alphabet + B.Alphabet <> 'ZZ'

ORDER BY

A.Alphabet + B.Alphabet

Basically the first CTE

L0 AS (SELECT CHAR(n) AS Alphabet FROM dbo.[fn_nums](90) WHERE n >=65)

Will give us 'A' to 'Z' and then we cross join itself with the second column is the rangeEnd with second alphabet is the next alphabet of the first column. (It's easier just try to match the result to the query)

But before that can run we'll need to create THE function

CREATE FUNCTION [dbo].[fn_nums](@n AS BIGINT) RETURNS TABLE

AS

RETURN

WITH

L0 AS(SELECT 1 AS c UNION ALL SELECT 1),

L1 AS(SELECT 1 AS c FROM L0 AS A, L0 AS B),

L2 AS(SELECT 1 AS c FROM L1 AS A, L1 AS B),

L3 AS(SELECT 1 AS c FROM L2 AS A, L2 AS B),

L4 AS(SELECT 1 AS c FROM L3 AS A, L3 AS B),

L5 AS(SELECT 1 AS c FROM L4 AS A, L4 AS B),

Nums AS(SELECT ROW_NUMBER() OVER(ORDER BY c) AS n FROM L5)

SELECT n FROM Nums WHERE n <= @n;

This function will return a table result with a single column n and start from 1 to the parameter @n super fast. Very useful function check out Inside TSQL querying book by Izik Ben Gan.

James