Question

我有一个以transaction_id为主键的表，还包含customer_id这是一个外键。

现在有一个列type有两个值：'Card'和'cash'。

现在一些客户已经使用了这两种付款方式。我想添加一个新列并将客户分类为＆＃34;只有卡＆＃34; ＆＃34;只有现金＆＃34;和＆＃34;两者＆＃34;。

Transaction id      Customer id Type
1                   100         Card   
2                   101         Cash 
3                   102         Card 
4                   103         Cash
5                   101         Card

因此，在此表中我想要一个新列＆＃39;付款方式＆＃39;由于他使用了两种付款方式，因此将客户101分类为两者。

Answer 1

您可以使用窗口功能：

select t.*,
       (case when min(type) over (partition by customerid) = max(type) over (partition by customerid)
             then 'Only ' + min(type) over (partition by customerid)
             else 'both'
        end)
from transactions t;

Answer 2

你可以做得更好并删除一些重新融合（仅限现金，卡只会在表格中重复，在这种情况下，我们更喜欢重复ID）。因此，您可以创建一个表格，例如payement_methods，其中包含两列，例如id和method，您将使用刚才提到的三个选项填充它（仅限现金，仅限卡片，两者都有，例如，您在transaction table列中payment_method_id（而不是您使用的类型列）。

例如

|id     | method       |
|1      | Cash only    |
|2      | Card Only    |
|3      | Both         |

交易表

|id     | other columns ...|payement method  |
|1      | other columns ...|1                |
|2      | other columns ...|3                |
//...

抱歉我的英语，祝你好运。

Answer 3

Create table tran1(Transactionid int ,   Customerid int  , Type varchar(100))

insert into tran1(Transactionid ,   Customerid , Type ) values
(1         ,          100    ,     'Card ' ),
(2         ,          101    ,     'Cash' ),
(3         ,          102    ,     'Card ' ),
(4         ,          103    ,     'Cash ' ),
(5         ,          101    ,     'Card ' )

alter table tran1 add NewType varchar(100)



Update tran1 set NewType ='Only card' where Customerid IN  (
select d.custid from (
 select Customerid as custid,SUM(case when [Type]='Card' then 1 else 0 end) card
 ,SUM(case when [Type]='Cash' then 1 else 0 end) cash
 from tran1
 group by Customerid)d
 where d.card=1  
 )


Update tran1 set NewType ='Only Cash' where Customerid IN  (
select d.custid from (
 select Customerid as custid,SUM(case when [Type]='Card' then 1 else 0 end) card
 ,SUM(case when [Type]='Cash' then 1 else 0 end) cash
 from tran1
 group by Customerid)d
 where d.cash=1  
 )

Update tran1 set NewType ='Both' where Customerid IN  (
select d.custid from (
 select Customerid as custid,SUM(case when [Type]='Card' then 1 else 0 end) card
 ,SUM(case when [Type]='Cash' then 1 else 0 end) cash
 from tran1
 group by Customerid)d
 where d.card=1 and cash=1
 )

Answer 4

如果你想要做的是分析付款方式，而不是在表中添加一列，那么做这样的事情可能会更好：

SELECT DISTINCT Table1.[Customer ID], T1.*
FROM Table1
CROSS APPLY (SELECT SUM(CASE WHEN [Type] = 'Cash' THEN 1 ELSE 0 END) AS Cash,
           SUM(CASE WHEN [Type] = 'Card' THEN 1 ELSE 0 END) AS Card
          FROM Table1 T WHERE T.[Customer ID] = Table1.[Customer ID]) T1

给你这样的结果：

CUSTOMER ID CASH    CARD
100          0       1
101          1       1
102          0       1
103          1       0

SQL：添加列并将其分类到类别中

4 个答案: