You can use Alan Burstein's PatExclude8K[/url]

WITH cteData AS (

SELECT x.String

FROM (VALUES('XDX114A77400'),

('1123AB00171')

) x (String)

)

SELECT d.String

, Letters = L.NewString

, Numbers = N.NewString

FROM cteData d

CROSS APPLY dbo.PatExclude8K(d.String,'%[^A-Za-z]%') L

CROSS APPLY dbo.PatExclude8K(d.String,'%[^0-9]%') N

ORDER BY d.String;