Select 每个 ID Table 个不存在的号码

Question

我是学习 TSQL 的新手，我正在努力获取我的 table 每个 ID 中不存在的数字。

示例：

CustomerID Group
1          1
3          1
6          1       
4          2
7          2

我想获取不存在的 ID 并且 select 他们这样

CustomerID Group
2          1       
4          1
5          1
5          2
6          2
....

..

使用 cte 的解决方案效果不佳或首先插入数据并执行不存在的 where 子句。

有什么想法吗？

Answer 1

如果您可以接受范围而不是每个范围的列表，那么一种有效的方法是使用 lead():

select group_id, (customer_id + 1) as first_missing_customer_id,
       (next_ci - 1) as last_missing_customer_id
from (select t.*,
             lead(customer_id) over (partition by group_id order by customer_id) as next_ci
      from t
     ) t
where next_ci <> customer_id + 1

Answer 2

交叉连接 2 个递归 CTE 以获得 [CustomerID] 和 [Group] 的所有可能组合，然后 LEFT 连接到 table:

declare @c int = (select max([CustomerID]) from tablename);
declare @g int = (select max([Group]) from tablename);
with 
  customers as (
    select 1 as cust
    union all
    select cust + 1 
    from customers where cust < @c
  ),
  groups as (
    select 1 as gr
    union all
    select gr + 1 
    from groups where gr < @g
  ),
  cte as (
    select *
    from customers cross join groups
  )
select c.cust as [CustomerID], c.gr as [Group] 
from cte c left join tablename t
on t.[CustomerID] = c.cust and t.[Group] = c.gr
where t.[CustomerID] is null
and c.cust > (select min([CustomerID]) from tablename where [Group] = c.gr)
and c.cust < (select max([CustomerID]) from tablename where [Group] = c.gr)

参见demo。
结果：

> CustomerID | Group
> ---------: | ----:
>          2 |     1
>          4 |     1
>          5 |     1
>          5 |     2
>          6 |     2

Select 每个 ID Table 个不存在的号码

Select non existing Numbers from Table each ID

sql

tsql

sql-server

range

recursive-query