[ Merge 拉链表] merge实现数据仓库历史拉链表

create table dm_channel_acct(    --渠道账户开户表
	cust_no         varchar(20),   --客户号
	channel_account varchar(20),   --渠道账号
	sing_org        varchar(10),   --开户机构
	sing_date       varchar(10),   --开户日期
	logout_date     varchar(10),   --销户日期
	acct_status     varchar(1),    --账号状态
	start_date      varchar(10),   --拉链开始日期
  end_date        varchar(10)    --拉链结束日期
);



create table ods_data(           --渠道账户开户表 数仓增量数据
	cust_no         varchar(20),   --客户号
	channel_account varchar(20),   --渠道账号
	sing_org        varchar(10),   --开户机构
	sing_date       varchar(10),   --开户日期
	logout_date     varchar(10),   --销户日期
	acct_status     varchar(1)    --账号状态
);

-- 放入原数据
insert into dm_channel_acct (cust_no, channel_account, sing_org, sing_date, logout_date, acct_status, start_date, end_date)
       values('1001', '201', 'zfb', '5701', '2020-01-05', '', 'Y', '2020-01-05', '9999-12-31')
       ;
       
insert into dm_channel_acct (cust_no, channel_account, sing_org, sing_date, logout_date, acct_status, start_date, end_date)
       values('1001', '202', 'jd', '5701', '2020-01-07', '', 'Y', '2020-01-07', '9999-12-31')
       ;

--设置数仓增量数据
insert into ods_data (cust_no, channel_account, sing_org, sing_date, logout_date, acct_status, start_date, end_date)
       values('1001', '201', 'zfb', '5701', '2020-01-05', '2020-01-15', 'N')
       ;
       
insert into ods_data (cust_no, channel_account, sing_org, sing_date, logout_date, acct_status, start_date, end_date)
       values('1001', '202', 'jd', '5701', '2020-01-05', '', 'Y')
       ;
       
insert into ods_data (cust_no, channel_account, sing_org, sing_date, logout_date, acct_status, start_date, end_date)
       values('1001', '202', 'cft', '5705', '2020-01-15', '', 'Y')
       ;

insert into ods_data (cust_no, channel_account, sing_org, sing_date, logout_date, acct_status, start_date, end_date)
       values('1002', '204', 'jd', '5705', '2020-01-15', '', 'Y')
       ;

insert into ods_data (cust_no, channel_account, sing_org, sing_date, logout_date, acct_status, start_date, end_date)
       values('1002', '201', 'jd', '5705', '2020-01-15', '', 'Y')
       ;
       
--写出要更新的语句，即dm_channel_acct和ods_data不同的记录
select 
       nvl(dm.cust_no, ods.cust_no) as cust_no
       ,nvl(dm.channel_account, ods.channel_account) as channel_account 
       ,nvl(dm.channel_type, ods.channel_type) as channel_type
       ,nvl(dm.sign_org, ods.sign_org) as sign_org
       ,nvl(dm.sign_date, ods.sign_date) as sign_date
       ,nvl(dm.logout_date, ods.logout_date) as logout_date
       ,nvl(dm.acct_status, ods.acct_status) as acct_status
       ,case when ods.channel_account is null then dm.start_date
             else '2020-01-17' 
         end as start_date
        ,case when ods.channel_account is null then '2020-01-17' 
              esle dm.end_date
          end as end_date       --ods表中有该表数据的结束日期
from ods_data ods 
full join dm_channel_acct dm 
       on ods.channel_account = dm.channel_account 
      and ods.cust_no = dm.cust_no 
      and ods.acct_status = dm.acct_status 
      and ods.channel_type = dm.channel_type 
where dm.channel_account is null 
   or (ods.channel_account is null and ccim.end_date = '999-12-31')  
;


--使用merge更新
merge into dm_channel_acct a 
using(
			select 
			       nvl(dm.cust_no, ods.cust_no) as cust_no
			       ,nvl(dm.channel_account, ods.channel_account) as channel_account 
			       ,nvl(dm.channel_type, ods.channel_type) as channel_type
			       ,nvl(dm.sign_org, ods.sign_org) as sign_org
			       ,nvl(dm.sign_date, ods.sign_date) as sign_date
			       ,nvl(dm.logout_date, ods.logout_date) as logout_date
			       ,nvl(dm.acct_status, ods.acct_status) as acct_status
			       ,case when ods.channel_account is null then dm.start_date
			             else '2020-01-17' 
			         end as start_date
			        ,case when ods.channel_account is null then '2020-01-17' 
			              esle dm.end_date
			          end as end_date       --ods表中有该表数据的结束日期
			from ods_data ods 
			full join dm_channel_acct dm 
			       on ods.channel_account = dm.channel_account 
			      and ods.cust_no = dm.cust_no 
			      and ods.acct_status = dm.acct_status 
			      and ods.channel_type = dm.channel_type 
			where dm.channel_account is null 
			   or (ods.channel_account is null and ccim.end_date = '999-12-31') 
) b 
on (a.cust_no = b.cust_no and a.channel_account = b.channel_account and a.channel_type = b.channel_type and a.channel_status = b.channel_status) 
when matched then 
     update 
        set a.acct_status = b.acct_status 
           ,logout_date = b.logout_date
           ,a.end_date = '2020-01-17'
when not matched then 
     insert (cust_no, channel_account, channel_type, sign_org, sign_date, logout_date, acct_status, start_date, end_date)
   values (b.cust_no, b.channel_account, b.channel_type, b.sign_org, b.sign_date, b.logout_date, b.acct_status, b.start_date, b.end_date)
;