张小咩的小姿生活
创建表用于测试：
删除表中的重复的数据，保存rowid最小的一个数据：
delete from tbl_a a
where
a.a_name in (select b.a_name from tbl_a b group by b.a_name having count(b.a_name)>1)
and
rowid not in (select min(rowid) from tbl_a c group by c.a_name having count(*)>1);
输出后的表：
