怎样用sql语句查找不同的姓

select distinct substring(姓名,1,1) from 表 where len(姓名)<=3

union all

select distinct substring(姓名,1,2) from 表 where len(姓名)>3

一般小于等于三个字的是单姓

大于三个字的是复姓

select * from 表 where n_id in

(select s_name from 表

group by s_name,n_money,s_zhipiao,s_date,s_lixi

having count(s_name)>1)

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