选择具有优先级值的非重复行

Question

我有一个包含带有测量值的行的表。 对于同一个批次 ID，可以指定多个度量。 我想在以下条件下获得正确的值：

• 如果给定批次只有一行，则度量有效
• 如果相同类型的行不止一行，则度量无效，返回的类型应为“无效”，值 = 0
• 如果不同类型的行不止一行（一个是“Acquired”，一个是“Verified”），则返回的行必须是“Verified”行

样本数据：

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;

示例输出：

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

Answer 1

你的逻辑有点难以理解。 您可以使用条件聚合做您想做的事情。 它认为的逻辑是：

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

使用窗口函数：

;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

演示在这里