SQL value of one column based on max values in other selected rows
Question
I am using the Northwind sample database table and I would like to find the top categoryId for each supplierId...
+-----------+----------------------------------+------------+------------+
| ProductID | ProductName | SupplierID | CategoryID |
+-----------+----------------------------------+------------+------------+
| 1 | Chai | 1 | 1 |
+-----------+----------------------------------+------------+------------+
| 2 | Chang | 1 | 1 |
+-----------+----------------------------------+------------+------------+
| 3 | Aniseed Syrup | 1 | 2 |
+-----------+----------------------------------+------------+------------+
| 4 | Chef Anton's Cajun Seasoning | 2 | 2 |
+-----------+----------------------------------+------------+------------+
| 5 | Chef Anton's Gumbo Mix | 2 | 2 |
+-----------+----------------------------------+------------+------------+
| 6 | Grandma's Boysenberry Spread | 3 | 2 |
+-----------+----------------------------------+------------+------------+
| 7 | Uncle Bob's Organic Dried Pears | 3 | 7 |
+-----------+----------------------------------+------------+------------+
| 8 | Northwoods Cranberry Sauce | 3 | 2 |
+-----------+----------------------------------+------------+------------+
| 9 | Mishi Kobe Niku | 4 | 6 |
+-----------+----------------------------------+------------+------------+
| 10 | Ikura | 4 | 8 |
+-----------+----------------------------------+------------+------------+
| 11 | Queso Cabrales | 5 | 4 |
+-----------+----------------------------------+------------+------------+
| 12 | Queso Manchego La Pastora | 5 | 4 |
+-----------+----------------------------------+------------+------------+
| 13 | Konbu | 6 | 8 |
+-----------+----------------------------------+------------+------------+
| 14 | Tofu | 6 | 7 |
+-----------+----------------------------------+------------+------------+
| 15 | Genen Shouyu | 6 | 2 |
+-----------+----------------------------------+------------+------------+
| 16 | Pavlova | 7 | 3 |
+-----------+----------------------------------+------------+------------+
| 17 | Alice Mutton | 7 | 6 |
+-----------+----------------------------------+------------+------------+
| 18 | Carnarvon Tigers | 7 | 8 |
+-----------+----------------------------------+------------+------------+
| 19 | Teatime Chocolate Biscuits | 8 | 3 |
+-----------+----------------------------------+------------+------------+
| 20 | Sir Rodney's Marmalade | 8 | 3 |
+-----------+----------------------------------+------------+------------+
| 21 | Sir Rodney's Scones | 8 | 3 |
+-----------+----------------------------------+------------+------------+
| 22 | Gustaf's Knäckebröd | 9 | 5 |
+-----------+----------------------------------+------------+------------+
| 23 | Tunnbröd | 9 | 5 |
+-----------+----------------------------------+------------+------------+
| 24 | Guaraná Fantástica | 10 | 1 |
+-----------+----------------------------------+------------+------------+
| 25 | NuNuCa Nuß-Nougat-Creme | 11 | 3 |
+-----------+----------------------------------+------------+------------+
| 26 | Gumbär Gummibärchen | 11 | 3 |
+-----------+----------------------------------+------------+------------+
| 27 | Schoggi Schokolade | 11 | 3 |
+-----------+----------------------------------+------------+------------+
| 28 | Rössle Sauerkraut | 12 | 7 |
+-----------+----------------------------------+------------+------------+
| 29 | Thüringer Rostbratwurst | 12 | 6 |
+-----------+----------------------------------+------------+------------+
| 30 | Nord-Ost Matjeshering | 13 | 8 |
+-----------+----------------------------------+------------+------------+
| 31 | Gorgonzola Telino | 14 | 4 |
+-----------+----------------------------------+------------+------------+
| 32 | Mascarpone Fabioli | 14 | 4 |
+-----------+----------------------------------+------------+------------+
| 33 | Geitost | 15 | 4 |
+-----------+----------------------------------+------------+------------+
| 34 | Sasquatch Ale | 16 | 1 |
+-----------+----------------------------------+------------+------------+
| 35 | Steeleye Stout | 16 | 1 |
+-----------+----------------------------------+------------+------------+
| 36 | Inlagd Sill | 17 | 8 |
+-----------+----------------------------------+------------+------------+
| 37 | Gravad lax | 17 | 8 |
+-----------+----------------------------------+------------+------------+
| 38 | Côte de Blaye | 18 | 1 |
+-----------+----------------------------------+------------+------------+
| 39 | Chartreuse verte | 18 | 1 |
+-----------+----------------------------------+------------+------------+
| 40 | Boston Crab Meat | 19 | 8 |
+-----------+----------------------------------+------------+------------+
| 41 | Jack's New England Clam Chowder | 19 | 8 |
+-----------+----------------------------------+------------+------------+
| 42 | Singaporean Hokkien Fried Mee | 20 | 5 |
+-----------+----------------------------------+------------+------------+
| 43 | Ipoh Coffee | 20 | 1 |
+-----------+----------------------------------+------------+------------+
| 44 | Gula Malacca | 20 | 2 |
+-----------+----------------------------------+------------+------------+
| 45 | Rogede sild | 21 | 8 |
+-----------+----------------------------------+------------+------------+
| 46 | Spegesild | 21 | 8 |
+-----------+----------------------------------+------------+------------+
| 47 | Zaanse koeken | 22 | 3 |
+-----------+----------------------------------+------------+------------+
| 48 | Chocolade | 22 | 3 |
+-----------+----------------------------------+------------+------------+
| 49 | Maxilaku | 23 | 3 |
+-----------+----------------------------------+------------+------------+
| 50 | Valkoinen suklaa | 23 | 3 |
+-----------+----------------------------------+------------+------------+
| 51 | Manjimup Dried Apples | 24 | 7 |
+-----------+----------------------------------+------------+------------+
| 52 | Filo Mix | 24 | 5 |
+-----------+----------------------------------+------------+------------+
| 53 | Perth Pasties | 24 | 6 |
+-----------+----------------------------------+------------+------------+
| 54 | Tourtière | 25 | 6 |
+-----------+----------------------------------+------------+------------+
| 55 | Pâté chinois | 25 | 6 |
+-----------+----------------------------------+------------+------------+
| 56 | Gnocchi di nonna Alice | 26 | 5 |
+-----------+----------------------------------+------------+------------+
| 57 | Ravioli Angelo | 26 | 5 |
+-----------+----------------------------------+------------+------------+
| 58 | Escargots de Bourgogne | 27 | 8 |
+-----------+----------------------------------+------------+------------+
| 59 | Raclette Courdavault | 28 | 4 |
+-----------+----------------------------------+------------+------------+
| 60 | Camembert Pierrot | 28 | 4 |
+-----------+----------------------------------+------------+------------+
| 61 | Sirop d'érable | 29 | 2 |
+-----------+----------------------------------+------------+------------+
| 62 | Tarte au sucre | 29 | 3 |
+-----------+----------------------------------+------------+------------+
| 63 | Vegie-spread | 7 | 2 |
+-----------+----------------------------------+------------+------------+
| 64 | Wimmers gute Semmelknödel | 12 | 5 |
+-----------+----------------------------------+------------+------------+
| 65 | Louisiana Fiery Hot Pepper Sauce | 2 | 2 |
+-----------+----------------------------------+------------+------------+
| 66 | Louisiana Hot Spiced Okra | 2 | 2 |
+-----------+----------------------------------+------------+------------+
| 67 | Laughing Lumberjack Lager | 16 | 1 |
+-----------+----------------------------------+------------+------------+
| 68 | Scottish Longbreads | 8 | 3 |
+-----------+----------------------------------+------------+------------+
| 69 | Gudbrandsdalsost | 15 | 4 |
+-----------+----------------------------------+------------+------------+
| 70 | Outback Lager | 7 | 1 |
+-----------+----------------------------------+------------+------------+
| 71 | Flotemysost | 15 | 4 |
+-----------+----------------------------------+------------+------------+
| 72 | Mozzarella di Giovanni | 14 | 4 |
+-----------+----------------------------------+------------+------------+
| 73 | Röd Kaviar | 17 | 8 |
+-----------+----------------------------------+------------+------------+
| 74 | Longlife Tofu | 4 | 7 |
+-----------+----------------------------------+------------+------------+
| 75 | Rhönbräu Klosterbier | 12 | 1 |
+-----------+----------------------------------+------------+------------+
| 76 | Lakkalikööri | 23 | 1 |
+-----------+----------------------------------+------------+------------+
| 77 | Original Frankfurter grüne Soße | 12 | 2 |
+-----------+----------------------------------+------------+------------+
Using the query
SELECT SupplierID, CategoryID, COUNT(CategoryID) AS Total FROM [dbo].[Products] GROUP BY CategoryID, SupplierID
I get the table
+------------+------------+-------+
| SupplierID | CategoryID | Total |
+------------+------------+-------+
| 1 | 1 | 2 |
+------------+------------+-------+
| 1 | 2 | 1 |
+------------+------------+-------+
| 2 | 2 | 4 |
+------------+------------+-------+
| 3 | 2 | 2 |
+------------+------------+-------+
| 3 | 7 | 1 |
+------------+------------+-------+
| 4 | 6 | 1 |
+------------+------------+-------+
| 4 | 7 | 1 |
+------------+------------+-------+
| 4 | 8 | 1 |
+------------+------------+-------+
| 5 | 4 | 2 |
+------------+------------+-------+
| 6 | 2 | 1 |
+------------+------------+-------+
| 6 | 7 | 1 |
+------------+------------+-------+
| 6 | 8 | 1 |
+------------+------------+-------+
| 7 | 1 | 1 |
+------------+------------+-------+
| 7 | 2 | 1 |
+------------+------------+-------+
| 7 | 3 | 1 |
+------------+------------+-------+
| 7 | 6 | 1 |
+------------+------------+-------+
| 7 | 8 | 1 |
+------------+------------+-------+
| 8 | 3 | 4 |
+------------+------------+-------+
| 9 | 5 | 2 |
+------------+------------+-------+
| 10 | 1 | 1 |
+------------+------------+-------+
| 11 | 3 | 3 |
+------------+------------+-------+
| 12 | 1 | 1 |
+------------+------------+-------+
| 12 | 2 | 1 |
+------------+------------+-------+
| 12 | 5 | 1 |
+------------+------------+-------+
| 12 | 6 | 1 |
+------------+------------+-------+
| 12 | 7 | 1 |
+------------+------------+-------+
| 13 | 8 | 1 |
+------------+------------+-------+
| 14 | 4 | 3 |
+------------+------------+-------+
| 15 | 4 | 3 |
+------------+------------+-------+
| 16 | 1 | 3 |
+------------+------------+-------+
| 17 | 8 | 3 |
+------------+------------+-------+
| 18 | 1 | 2 |
+------------+------------+-------+
| 19 | 8 | 2 |
+------------+------------+-------+
| 20 | 1 | 1 |
+------------+------------+-------+
| 20 | 2 | 1 |
+------------+------------+-------+
| 20 | 5 | 1 |
+------------+------------+-------+
| 21 | 8 | 2 |
+------------+------------+-------+
| 22 | 3 | 2 |
+------------+------------+-------+
| 23 | 1 | 1 |
+------------+------------+-------+
| 23 | 3 | 2 |
+------------+------------+-------+
| 24 | 5 | 1 |
+------------+------------+-------+
| 24 | 6 | 1 |
+------------+------------+-------+
| 24 | 7 | 1 |
+------------+------------+-------+
| 25 | 6 | 2 |
+------------+------------+-------+
| 26 | 5 | 2 |
+------------+------------+-------+
| 27 | 8 | 1 |
+------------+------------+-------+
| 28 | 4 | 2 |
+------------+------------+-------+
| 29 | 2 | 1 |
+------------+------------+-------+
| 29 | 3 | 1 |
+------------+------------+-------+
As you can see supplier 1 makes 2 category 1 products and 1 catergory 2 product. Therefore the first line in the query should read
+------------+------------+-------+
| SupplierID | CategoryID | Total |
+------------+------------+-------+
| 1 | 1 | 2 |
+------------+------------+-------+
Next should be supplierId #2 which makes a total of 4 category 2 products. The final table should look like this...
+------------+------------+-------+
| SupplierID | CategoryID | Total |
+------------+------------+-------+
| 1 | 1 | 2 |
+------------+------------+-------+
| 2 | 2 | 4 |
+------------+------------+-------+
| 3 | 2 | 2 |
+------------+------------+-------+
| 4 | 6 | 1 |
+------------+------------+-------+
| 5 | 4 | 2 |
+------------+------------+-------+
| 6 | 2 | 1 |
+------------+------------+-------+
| 7 | 1 | 1 |
+------------+------------+-------+
| 8 | 3 | 4 |
+------------+------------+-------+
| 9 | 5 | 2 |
+------------+------------+-------+
| 11 | 3 | 3 |
+------------+------------+-------+
| 12 | 1 | 1 |
+------------+------------+-------+
| 13 | 8 | 1 |
+------------+------------+-------+
| 14 | 4 | 3 |
+------------+------------+-------+
| 15 | 4 | 3 |
+------------+------------+-------+
| 16 | 1 | 3 |
+------------+------------+-------+
| 17 | 8 | 3 |
+------------+------------+-------+
| 18 | 1 | 2 |
+------------+------------+-------+
| 19 | 8 | 2 |
+------------+------------+-------+
| 20 | 1 | 1 |
+------------+------------+-------+
| 21 | 8 | 2 |
+------------+------------+-------+
| 22 | 3 | 2 |
+------------+------------+-------+
| 23 | 3 | 2 |
+------------+------------+-------+
| 24 | 5 | 1 |
+------------+------------+-------+
| 25 | 6 | 2 |
+------------+------------+-------+
| 26 | 5 | 2 |
+------------+------------+-------+
| 27 | 8 | 1 |
+------------+------------+-------+
| 28 | 4 | 2 |
+------------+------------+-------+
| 29 | 2 | 1 |
+------------+------------+-------+
| 29 | 3 | 1 |
+------------+------------+-------+
I know a lot of suppliers only make one item for a given category and this isn't a great example but just trying to learn here.
Thanks
3 answers
solution1
0 2020-01-05 20:15:12
I think you can make use of row number based on partition by supplier and then use aggregate function along with row number for ranking. Then only select the one where you have more rows for a given supplier. I just took some part of your sample data and did it in this way.
with cte as (
select 1 as ProductID, 'Chai' as ProductNmae, 1 as SupplierID, 1 as CategoryID union all
select 2 as ProductID, 'Chang' as ProductNmae, 1 as SupplierID, 1 as CategoryID union all
select 3 as ProductID, 'Aniseed Syrup' as ProductNmae, 1 as SupplierID, 2 as CategoryID union all
select 4 as ProductID, 'Chef Anton''s Cajun Seasoning' as ProductNmae, 2 as SupplierID, 2 as CategoryID union all
select 5 as ProductID, 'Chef Anton''s Gumbo Mix' as ProductNmae, 2 as SupplierID, 2 as CategoryID union all
select 6 as ProductID, 'Grandma''s Boysenberry Spread' as Product_name , 3 as SupplierID, 2 as CategoryID union all
select 7 as ProductID, 'Uncle Bob''s Organic Dried Pears' as Product_name , 3 as SupplierID, 7 as CategoryID union all
select 8 as ProductID, 'Northwoods Cranberry Sauce' as Product_name , 3 as SupplierID, 2 as CategoryID )
select t.SupplierID, t.CategoryID, t.total from (
select supplierID, CategoryID , ROW_NUMBER() over (partition by supplierID order by count(1) desc) rownum, count(1) total from cte
group by supplierID, CategoryID ) t
where t.rownum = 1
Output:
SupplierID CategoryID total
1 1 2
2 2 2
3 2 2
solution2
0 2020-01-05 20:17:35
First you have to generate the category counts by supplier, then you have to rank them from highest to lowest, and finally select only the highest. In the following query, I've done that by using nested queries:
-- Select only the top category counts by supplier
SELECT
[SupplierID],
[CategoryID],
[Total]
FROM (
-- Rank category counts by supplier
SELECT
*,
RANK() OVER (PARTITION BY [SupplierID] ORDER BY [Total] DESC) AS [Rank]
FROM (
-- Generate category counts by supplier
SELECT
[SupplierID],
[CategoryID],
COUNT(*) AS [Total]
FROM [Products]
GROUP BY
[SupplierID],
[CategoryID]
) AS SupplierCategoryCounts
) AS RankedSupplierCategoryCounts
WHERE [Rank] = 1
ORDER BY [SupplierID]
solution3
0 2020-01-05 20:33:40
In Sql server you can write a query as:
select SupplierID ,
CategoryID ,
Total
from (
select
SupplierID ,
CategoryID ,
Total ,
ROW_NUMBER() over (partition by SupplierID order by Total desc) as rownum
from (
SELECT SupplierID
, CategoryID
, COUNT(CategoryID) AS Total
FROM [dbo].[Products]
GROUP BY CategoryID, SupplierID
) as Innertable
) as Outertable
where rownum = 1
order by SupplierID
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