编写 SQL 查询以返回已预订多年但未在 2021 年预订的客户

Question

我需要编写一个查询来回答以下问题：

“提供 2018-2020 年期间但未在 2021 年预订的客户的报告”

我生成了以下查询以按年份分离出如下所示的数据，每个表代表每年的客户预订量。

按年份获取客户预订：

with active_2018 as
(
    select c.id, c.email, c.telephone                       
    from customer c                     
    join booking b on b.customer_id = c.id                      
    where to_char(b.date_created, 'YYYY') = '2018'                      
    group by 1, 2, 3                    
),      
active_2019 as 
(
    select c.id, c.email, c.telephone                       
    from customer c                     
    join booking b on b.customer_id = c.id                      
    where to_char(b.date_created, 'YYYY') = '2019'                      
    group by 1, 2, 3                    
),  
active_2020 as 
(
    select c.id, c.email, c.telephone                       
    from customer c                     
    join booking b on b.customer_id = c.id                      
    where to_char(b.date_created, 'YYYY') = '2020'                      
    group by 1, 2, 3                    
),
active_2021 as 
(
    select c.id, c.email, c.telephone                       
    from customer c                     
    join booking b on b.customer_id = c.id                      
    where to_char(b.date_created, 'YYYY') = '2021'                      
    group by 1, 2, 3                    
)

我意识到以下尝试是错误的，但到目前为止这是我最好的尝试，我认为这个查询是说显示在 2018 年和 2019 年和 2020 年而不是在 2021 年预订的客户预订。这是错误的，因为我实际上需要那些已在 2018 年或 2019 年或 2020 年预订，但未在 2021 年预订。

尝试 #1 - 失败：

select distinct(a.id), a.email, a.telephone     
from active_2018 a on a.id = a.id 
join active_2019 b on a.id = b.id   
join active_2020 c on a.id = c.id           
where a.id not in (select id from active_2021)      

Answer 1

编辑（再次..]）：在下面的评论和查看文档之后。你实际上需要一个工会。因为它们可能在 2018 年、2019 年或 2020 年，但不是 2021 年。“或”是我认为你需要工会而不是加入的原因。除了 2021 年之外，不是每一年都预订的人。

'
 select distinct(a.id) as id, a.email as email, a.telephone as telephone     
 from active_2018
 where a.id not in (select id from active_2021)
 union
 select distinct(b.id) as id, b.email as email, b.telephone as telephone     
 from active_2018 as b
 where b.id not in (select id from active_2021)
 union
 select distinct(c.id) as id, c.email as email, c.telephone as telephone     
 from active_2018 as c
 where c.id not in (select id from active_2021);               
 
'