T-SQL query sample for alpha-numeric characters

This sample uses higher than, less than, ISNumeric, and expresions with Varchar fields.

Declare @esn Table(id int primary key,Num varchar(11))
insert into @esn
values	(1,'123456AB'),
		(2,'123ABC65'),
		(3,'12563254'),
		(4,'15647894'),
		(5,'15698736'),
		(6,'8564589A'),
		(7,'ABC25632'),
		(8,'C1111111'),
		(9,'ADFGETHQ'),
		(10,'0SARGENTO1'),
		(11,'M67AB8340Z')

/*Query only Numeric*/
Select *
from @esn 
where ISNUMERIC(Num)=1
/*Query Start with a Letter*/
 Select *
 from @esn 
 where Num > 'A'
 /*End with a letter*/
 Select *
from @esn 
where right(Num,1) > '9'
/*Only Letters*/
Select *
from @esn 
where  Num  Not LIKE '%[^A-Z]%'