利用Sql脚本，删除数据库里重复数据

在数据库中经常会遇到大量的重复数据，如果这些脏数据需要清除，那下面的内容就非常是为你量身定做的哦，若不是，请忽略！

第一步，假设有个dept数据表，内容如下：

• 查找重复项

  select dname from dept group by dname having count(dname) > 1;

• 筛选出保留项，即不能删除的

  select min(deptno) -- max(deptno)
  from dept
  group by dname

• 删除重复项

  delete from dept where
  dname in (select dname from dept group by dname having count(dname) > 1)
  and deptno not in (select min(deptno) as detpno from dept group by dname having count(dname) > 1);

  注: 上述sql脚本，可运行于 MS SQL , Oracle

• MySql下删除重复项

  delete from dept where
  dname in (select * from(select dname from dept group by dname having count(dname) > 1) a)