更新与现有表的字段自动递增逻辑

Question

我有以下数据的表格，

  Product 
----------------------------- 
ID Name ProductTypeID Order 
1  A  1   0 
2  B  1   0 
3  D  2   0 
4  C  2   0 
----------------------------------- 
----------------------------------- 
----------------------------------- 

我需要更新的顺序，使其值成为，

  Product 
----------------------------- 
ID Name ProductTypeID Order 
1  A  1   1 
2  B  1   2 
3  D  2   1 
4  C  2   2 
----------------------------------- 
----------------------------------- 
----------------------------------- 

见它将为每个ProductTypeID增加Order作为AutoIncrement。

Answer 1

你想要做什么的就是那种分区中的记录。 query to do what you want is this：

WITH sorted AS (
    SELECT id, ROW_NUMBER() OVER(PARTITION BY ProductTypeId ORDER BY id ASC) as rownum 
    FROM product 
) 
UPDATE product 
SET [order] = s.rownum 
FROM product p 
    INNER JOIN sorted s on (p.id = s.id); 

Answer 2

现在尝试

Update product Set [order]= Case when Not Exists (Select * from 
product a where a.ProductTypeID =product.ProductTypeID and a.id 
<product.ID) 
    tHEN 1 
    eLSE 
    ((Select Count([ORDER]) from product b where 
    b.ProductTypeID =product.ProductTypeID and b.ID <product.id)+1) 
    eND