/*
	統計一個表中某個字符出現最多的字母
*/
--創建數據測試環境
create table #tb(a varchar(200))
insert into #tb
	select 'abcdasdlfjaslk;dfqwoieurwhft'
	union all select 'a;sldkjfal;sopqwhtdlkdafrfgsgasdfh'
	union all select 'asldfkworufgsea87y9oqwpe tchgwccmnqnw3 '

--為字符分拆準備臨時表,top 200 是根據要分拆的字符串的最大長度而定的,
--在測試中,因為a字段的最大為200,故這里用 top 200
select top 200 id=identity(int,1,1)
	into #aa from
	(select top 100 id from syscolumns) a
	,(select top 100 id from syscolumns) b
	,(select top 100 id from syscolumns) c

--得到結果
select top 1 substring(a,b.id,1)
	from #tb a,#aa b 
	where substring(a.a,b.id,1)<>''
	group by substring(a.a,b.id,1)
	order by sum(1) desc

drop table #tb,#aa