重複數據查詢、刪除 group by having使用

--查詢重複記錄，單個字段或多個字段約束
 select 重複字段名
   from 表名
  group by 重複字段名
 having count(重複字段名) > 1

例：
 select t.mark_id
   from LOSS_F_MARK_STATUS t
  where t.sbtype = '1'
  group by t.mark_id
 having count(t.mark_id) >= 2
--或者  having count(t.mark_id) > 1

例：
 select t.mark_id, t.obj_id
   from LOSS_F_MARK_STATUS t
  where t.sbtype = '1'
  group by t.mark_id, t.obj_id
 having count(t.mark_id) > 1

--查詢表中重複記錄

例：
select *  
 from LOSS_F_MARK_STATUS t1
 where t1.mark_id in (select t.mark_id
                        from LOSS_F_MARK_STATUS t
                       where t.sbtype = '1'
                       group by t.mark_id
                      having count(t.mark_id) >= 2)

--刪除重複記錄，只保留一條

例：
delete
  from LOSS_F_MARK_STATUS t1
 where t1.mark_id in (select t.mark_id
                        from LOSS_F_MARK_STATUS t
                       where t.sbtype = '1'
                       group by t.mark_id
                      having count(t.mark_id) >= 2)
   --and t1.sbtype = '1'
   and rowid not in
       (select max(rowid) from LOSS_F_MARK_STATUS t2 group by t2.mark_id)
--保留rowid 最大的記錄

--刪除重複記錄，保留rowid最小的記錄
delete
  from LOSS_F_MARK_STATUS t1
 where t1.mark_id in (select t.mark_id
                        from LOSS_F_MARK_STATUS t
                       where t.sbtype = '1'
                       group by t.mark_id
                      having count(t.mark_id) >= 2)
   --and t1.sbtype = '1'
   and rowid not in
       (select min(rowid) from LOSS_F_MARK_STATUS t2 group by t2.mark_id having count(*)>1) 
--不好用，刪除3條以上記錄好用。刪除重複兩條記錄時，把只有一條的記錄刪掉了