假设有一张tabA的表，以其中的name字段判断是否重复
一. 查找表中多余的重复记录，重复记录根据表中的单个字段来判断
select * from tabA where name in (select name from tabA group by name having count (name) > 1)
二. 删除表中多余重复的记录，只保留其中一条
delete from tabA where
name in (select name from tabA group by name having count (name) > 1)
and rowid not in (select min(rowid) from tabA group by name having count(name)>1)