SQL 如果满足条件，则将状态应用到帐户的每一行

Question

我有以下数据集，

并想创建一个“标志”，其中任何具有 bucket_type = 'Self-pay' 和 bucket_status = 'Outstanding' 的帐户都会收到描述“Self-为与该帐户有关的所有行支付未结款项”。其他实例可视为“N/A”。像这样：

我对 row_count()、partition by 和 case 语句有些熟悉，但我不确定如何将它们组合在一起以实现我想要的。我有以下代码，但我的案例陈述被绊倒了。

select 
account
,bucket_type
,bucket_status
,case when bucket_type = 'Self-pay' and bucket_status = 'Outstanding' over (partition by account)
then 'Self-pay Outstanding' else null end 
from account_table

非常感谢！

Answer 1

你可以使用条件 window max():

select t.*,
    case max(case when bucket_type = 'Self-pay' and bucket_status = 'Outstanding' then 1 else 0 end) over(partition by account) 
        when 1 then 'Self-pay Outstanding'
        else 'NA'
    end as flag
from mytable t

另一种方法是 exists 具有相关子查询的条件：

select t.*,
    case when exists (select 1 from mytable t1 where t1.account = t.account and t1.bucket_type = 'Self-pay' and t1.bucket_status = 'Outstanding')
        then 'Self-pay Outstanding'
        else 'NA'
    end as flag
from mytable t

我真的不知道哪种解决方案会更好。 window 函数更简洁；子查询将利用 (account, bucket_type, bucket_status).

上的索引

Answer 2

用普通 TABLE 表达式试试这个

SQL Fiddle

MS SQL Server 2017 架构设置:

CREATE TABLE Account_Table
(
  Account VarChar(50),
  Bucket_Type VarChar(50),
  Bucket_Status VARCHAR(50)
 );
 
 INSERT INTO Account_Table
 VALUES
  ('A', 'Self-pay', 'Outstanding'),
  ('A', 'Prebilled', 'Closed'),
  ('A', 'Primary', 'Closed'),
  ('B', 'Self-pay', 'Closed'),
  ('B', 'Prebilled', 'Closed'),
  ('B', 'Primary', 'Outstanding'),
  ('C', 'Primary', 'Closed'),
  ('C', 'Secondary', 'Outstanding')

查询 1:

WITH CTE
AS
(
  SELECT DISTINCT Account, 'Self-pay Outstanding' as Flag
  FROM Account_Table
  WHERE 
    Bucket_Type = 'Self-Pay' AND
    Bucket_Status = 'Outstanding'
 )
 SELECT A.Account, A.Bucket_Type, A.Bucket_Status, COALESCE(CTE.Flag, 'N/A') AS Flag
 FROM Account_Table A
 LEFT JOIN CTE
   ON CTE.Account = A.Account

Results:

| Account | Bucket_Type | Bucket_Status |                 Flag |
|---------|-------------|---------------|----------------------|
|       A |    Self-pay |   Outstanding | Self-pay Outstanding |
|       A |   Prebilled |        Closed | Self-pay Outstanding |
|       A |     Primary |        Closed | Self-pay Outstanding |
|       B |    Self-pay |        Closed |                  N/A |
|       B |   Prebilled |        Closed |                  N/A |
|       B |     Primary |   Outstanding |                  N/A |
|       C |     Primary |        Closed |                  N/A |
|       C |   Secondary |   Outstanding |                  N/A |

SQL 如果满足条件，则将状态应用到帐户的每一行

SQL apply status to each row of account if condition is met

sql

sql-server

subquery

window-functions