SQL Conditional WHERE Statement

Hi, is it possible to do a conditional WHERE in T-SQL? I have a table with a column that consists of a reference that starts with either a single alpha character or two alpha characters followed by four numeric digits (the numeric portion is always unique but the alpha isn’t). E.g. A1234, AB1235, AB1236, C1237, HT1238. What I want to do is select a range of rows based on the numeric portion of this reference column. In other words I want to select say 50 rows starting from row 1000 (rows 1000 to 1050) regardless of whether there is one or two alpha characters preceding the numerics.The Stored procedure I have so far works (using COUNT for testing) for selecting a range of rows that has two alpha's at the start. However, if I simply add an OR to the WHERE to select rows where there is a single alpha in the reference column, when a single alpha reference is found it will fail the first logical check for two alpha's giving an error condition. Therefore, how can I incorporate a conditional WHERE using IF or some alternative method, so that it will also give me all the rows in the number sequence that start with either single or double alpha's within the same SELECT / WHERE statement?



Thanks for any help.ALTER PROCEDURE [dbo].[sp_Test]

(
@startRef int,
@endRef int
)

AS

BEGIN

SELECT Count(*) FROM myTable
WHERE ((SUBSTRING(Ref,3,LEN(Ref)-2) BETWEEN @startRef AND (@startRef + @endRef)))

END
RETURN