问题
I have a table called productLocation, and its data structure as follows, SQLFiddle
+--------------+-------------+-----------+
| FkLocationId | FkProductId | SortValue |
+--------------+-------------+-----------+
| 1 | 100 | 0 |
+--------------+-------------+-----------+
| 1 | 101 | 0 |
+--------------+-------------+-----------+
| 1 | 102 | 0 |
+--------------+-------------+-----------+
| 1 | 103 | 2 |
+--------------+-------------+-----------+
| 1 | 104 | 1 |
+--------------+-------------+-----------+
| 1 | 105 | 3 |
+--------------+-------------+-----------+
| 2 | 100 | 0 |
+--------------+-------------+-----------+
| 2 | 101 | 0 |
+--------------+-------------+-----------+
| 2 | 102 | 0 |
+--------------+-------------+-----------+
| 2 | 103 | 1 |
+--------------+-------------+-----------+
| 2 | 104 | 3 |
+--------------+-------------+-----------+
| 2 | 105 | 2 |
+--------------+-------------+-----------+
| 3 | 100 | 0 |
+--------------+-------------+-----------+
| 3 | 101 | 0 |
+--------------+-------------+-----------+
| 3 | 102 | 0 |
+--------------+-------------+-----------+
| 3 | 103 | 1 |
+--------------+-------------+-----------+
| 3 | 104 | 2 |
+--------------+-------------+-----------+
For each location have its own sorting order for products. But some of the products have 0 as the SortValue
Now I need to write a query to update SortValue as,
If I consider one location, FkLocationId = 1
+--------------+-------------+-----------+
| FkLocationId | FkProductId | SortValue |
+--------------+-------------+-----------+
| 1 | 100 | 0 |
+--------------+-------------+-----------+
| 1 | 101 | 0 |
+--------------+-------------+-----------+
| 1 | 102 | 0 |
+--------------+-------------+-----------+
| 1 | 103 | 2 |
+--------------+-------------+-----------+
| 1 | 104 | 1 |
+--------------+-------------+-----------+
| 1 | 105 | 3 |
+--------------+-------------+-----------+
In the above data table, you can see, FkProductId = 100,101,102 have 0 as the SortValue. I need to update its sortValue as order by FkProductId descending order. I need to update its like
+--------------+-------------+-----------+
| FkLocationId | FkProductId | SortValue |
+--------------+-------------+-----------+
| 1 | 100 | 3 |
+--------------+-------------+-----------+
| 1 | 101 | 2 |
+--------------+-------------+-----------+
| 1 | 102 | 1 |
+--------------+-------------+-----------+
And also update the previous SortValue by one by one.
Then the complete output should be,
+--------------+-------------+-----------+
| FkLocationId | FkProductId | SortValue |
+--------------+-------------+-----------+
| 1 | 100 | 3 |
+--------------+-------------+-----------+
| 1 | 101 | 2 |
+--------------+-------------+-----------+
| 1 | 102 | 1 |
+--------------+-------------+-----------+
| 1 | 103 | 5 |
+--------------+-------------+-----------+
| 1 | 104 | 4 |
+--------------+-------------+-----------+
| 1 | 105 | 6 |
+--------------+-------------+-----------+
Is this possible to do? I'm really confused about this, please help me to solve this. Thank you
Updated:
Suppose I have another table as product. And its data structure as follows,
+-----------+-----------+
| ProdcutId | SortValue |
+-----------+-----------+
| 100 | 0 |
+-----------+-----------+
| 101 | 0 |
+-----------+-----------+
| 107 | 0 |
+-----------+-----------+
| 108 | 1 |
+-----------+-----------+
| 109 | 2 |
+-----------+-----------+
| 110 | 6 |
+-----------+-----------+
| 111 | 5 |
+-----------+-----------+
| 112 | 4 |
+-----------+-----------+
| 113 | 3 |
+-----------+-----------+
I also need to do same thing for this table as well, How can I do it
Expected Output:
+-----------+-----------+
| ProdcutId | SortValue |
+-----------+-----------+
| 100 | 3 |
+-----------+-----------+
| 101 | 2 |
+-----------+-----------+
| 107 | 1 |
+-----------+-----------+
| 108 | 4 |
+-----------+-----------+
| 109 | 5 |
+-----------+-----------+
| 110 | 9 |
+-----------+-----------+
| 111 | 8 |
+-----------+-----------+
| 112 | 7 |
+-----------+-----------+
| 113 | 6 |
+-----------+-----------+
回答1:
Following is a sample query for you to check and use the same logic for your update process using CTE-
DEMO HERE
Important Note: Update is a risky process and you should try with your test data first.
WITH CTE
AS
(
SELECT *,
(
SELECT COUNT(*)
FROM #Temp B
WHERE B.FkLocationId = A.FkLocationId
AND SortValue = 0
) Zero_Count,
-- The above Zero count is a simple count of rows with 0
-- for a specific FkLocationId. This is for adding to other
-- rows where there are already value in column SortValue. The logic
-- is simple, the number of row with 0 in column SortValue,
-- should be add to existing value where there is value not equal 0.
ROW_NUMBER() OVER (PARTITION BY FkLocationId ORDER BY SortValue ASC, FkProductId DESC) RN
-- ROW_NUMBER is simply creating the Number you should replace 0 by.
-- As you are looking for 1 to start for the MAX FkProductId with 0,
-- I applied DESC order on that column
FROM #Temp A
)
UPDATE A
SET A.SortValue =
CASE
WHEN A.SortValue = 0 THEN B.RN
-- RN is created in such way, so that you can directly
-- Replace your value in column SortValue by RN if SortValue = 0
ELSE A.SortValue + B.Zero_Count
-- IF SortValue contains already value > 0,
-- You need to just increment the value with Number
-- of rows is there with value 0. I have calculated that value
-- by a sub query in the CTE you can check.
END
FROM #Temp A
INNER JOIN CTE B ON A.FkLocationId = B.FkLocationId
AND A.FkProductId = B.FkProductId
SELECT * FROM #Temp
Just use your "table_name" where I have used #temp
回答2:
with cte as
(select FkLocationId, FkProductId, SortValue,
ROW_NUMBER() over(partition by FkLocationId order by sortvalue,FkProductId desc) new_sort_value
from productLocation where FkLocationId =1 --and SortValue =0
)
update pl SET
pl.SortValue = c.new_sort_value
from productLocation pl inner join cte c
on pl.FkLocationId = c.FkLocationId and pl.FkProductId = c.FkProductId
Select * from productLocation where FkLocationId =1 order by FkProductId
The core of the approach taken by me is based row_number window function, which partitions data over fkproductid sorted by sortvalue and fkproductid in descending manner.
There are 2 queries involved, although could have been done is single, but for simplicity's sake i have used common table expression (cte)
CTE derived from query one is used as joining table in second update query.
I have left much to self exploration, remember its imperative to think in term of sets.
来源：https://stackoverflow.com/questions/62166993/how-to-increment-column-by-one-group-wise