SQL Server：當NULL時添加max（column_value）+1

Question

我有兩個表，即Test2和Test3。

我在Test2表中有10條記錄。並且在Test3表中沒有記錄。

在Test2表中，我在列ColumnID列中有一些空值。

我想從表Test2和選擇記錄將記錄插入到表Test3當出現空 值我只是想和最大添加它ColumnID列加1

表：Test2的

Create table Test2 
(
    ColumnID int 
); 

插入：

INSERT INTO Test2 values(1); 
INSERT INTO Test2 values(2); 
INSERT INTO Test2 values(3); 
INSERT INTO Test2 values(5); 
INSERT INTO Test2 values(8); 
INSERT INTO Test2 values(null); 
INSERT INTO Test2 values(null); 
INSERT INTO Test2 values(null); 
INSERT INTO Test2 values(null); 
INSERT INTO Test2 values(null); 

預期結果：

表：Test3的

ColumnID 
---------------- 
1 
2 
3 
5 
8 
9 --Increament by 1 to max of id 
10 --increment by 1 to max of id 
11 
12 
13 

嘗試：1

INSERT INTO Test3 
SELECT Case WHEN ColumnID IS NOT NULL then ColumnID else max(ColumnID)+1 end as Column_ID 
from Test2 
group by ColumnID; 

嘗試：2

DECLARE @count int 
DECLARE @i int = 1 
SELECT @count = COUNT(*) FROM Test2; 

WHILE (@i <= @count) 
BEGIN 
    INSERT INTO Test3 
    SELECT Case WHEN ColumnID IS NOT NULL then ColumnID else max(ColumnID)+1 end as Column_ID 
    from Test2 
    group by ColumnID; 
    set @i = @i + 1; 
END 
GO 

Answer 1

試試這個：

INSERT INTO Test3 
SELECT COALESCE(ColumnID, 
       ROW_NUMBER() OVER (PARTITION By ColumnID 
            ORDER BY ColumnID) + 
       MAX(ColumnID) OVER()) 
FROM Test2 

Demo here