CREATE TABLE #temp(mixedvalues VARCHAR(10));
INSERT INTO #temp
VALUES('T863'),
('356'),
('F5963'),
('563'),
('3659'),
('340T');
;WITH CTE AS(
SELECT SUBSTRING(mixedvalues,
PATINDEX('%[0-9]%', mixedvalues),
(LEN(mixedvalues)-PATINDEX('%[0-9]%',REVERSE(mixedvalues))+1)) AS
NumericValues FROM #TEMP)
SELECT * FROM CTE WHERE NumericValues between 355 and 1000;
-----------------
NumericValues
--------------
NumericValues
863
356
563