清除冗余记录的SQL语句-数据库专栏,SQL Server

问题：设表t中有五个字段a，b，c，d，id，其中id字段是为自动增量整型字段(唯一值)。业务数据生成时有重复插入现象，现需对a、b、c、d四字段完全一样的脏数据进行清理，要求设计一sql语句，对四个字段完全一样的记录，仅保留id最小的一条，其余作删除处理。

delete from t where [id] in
(
 select [id] from t where a in
  (select a  from t group by a,b,c,d having count(*)>1)
 and [id]<>
  (select min(id) as minid  from t group by a,b,c,d having count(*)>1)
)

更正：
delete from t
where t.id not in (select min(id) from t group by t.a,t.b,t.c,t.d)