選擇具有優先級值的非重復行

Question

我有一個包含帶有測量值的行的表。 對於同一個批次 ID，可以指定多個度量。 我想在以下條件下獲得正確的值：

• 如果給定批次只有一行，則度量有效
• 如果相同類型的行不止一行，則度量無效，返回的類型應為“無效”，值 = 0
• 如果不同類型的行不止一行（一個是“Acquired”，一個是“Verified”），則返回的行必須是“Verified”行

樣本數據：

create table measures (
  batch  int,
  type   varchar(24),
  value int
);

insert into measures select 01,'Verified',10;
insert into measures select 02,'Acquired',34;
insert into measures select 03,'Verified',22;
insert into measures select 03,'Verified',24;
insert into measures select 04,'Verified',32;
insert into measures select 04,'Acquired',34;
insert into measures select 05,'Acquired',42;
insert into measures select 05,'Acquired',44;

示例輸出：

01   Verified   10
02   Acquired   34
03   Invalid    0
04   Verified   32
05   Invalid    0

Answer 1

你的邏輯有點難以理解。 您可以使用條件聚合做您想做的事情。 它認為的邏輯是：

select batch,
       (case when count(*) = 1 then max(type)
             when min(type) = max(type) then 'Invalid'
             else coalesce(max(case when type = 'Verified' then 'Verified' end), 'Invalid')
        end) as type,
       (case when count(*) = 1 then max(value)
             when min(type) = max(type) then 0
             else coalesce(max(case when type = 'Verified' then value end), 0)
        end) as value
from measures m
group by batch;

Answer 2

使用窗口函數：

;WITH CountTypesPerBatch AS
(
    SELECT batch, type, value,
           COUNT(CASE WHEN type = 'Verified' THEN 1 END) 
              OVER (PARTITION BY batch) AS verified,
           COUNT(CASE WHEN type = 'Acquired' THEN 1 END) 
              OVER (PARTITION BY batch) AS acquired,
           ROW_NUMBER() OVER (PARTITION BY batch 
                              ORDER BY IIF(type='Verified',1, 2)) seq
    FROM measures
)
SELECT DISTINCT batch, 
       CASE 
          WHEN verified > 1 OR acquired > 1 THEN 'invalid' 
          WHEN verified = 1 THEN 'verified'
          ELSE 'acquired'
       END,
       CASE 
          WHEN verified > 1 OR acquired > 1 THEN 0
          ELSE value
       END
FROM CountTypesPerBatch
WHERE seq = 1

演示在這里