REGEX，以下範例以身份証為例
if object_id('tempdb..#T') is not null
drop table #T
select 'A123456789' str into #T
union all select '123456789'
union all select 'ABCDEFG'
union all select 'AA12345678'
--全為數字
select * from #T where str not like '%[^0-9]%'
--全為英文字
select * from #T where str not like '%[^a-zA-Z]%'
--第一碼為英文,後面為數字
select * from #T
where left(str,1) not like '%[^a-zA-Z]%'
and substring(str,2,LEN(str)-1) not like '%[^0-9]%'
--第一、二碼為英文,後面為數字
select * from #T
where (left(str,1) not like '%[^a-zA-Z]%' and substring(str,2,LEN(str)-1) not like '%[^0-9]%')
or (left(str,2) not like '%[^a-zA-Z]%' and substring(str,3,LEN(str)-2) not like '%[^0-9]%')