How to create a sql query get the 2nd to Max result in table?

Question

I have a table in snowflake and I want to see the results for the max date and 2nd to Max date. I wrote a query below which gives the results for max date

SELECT MAX(FILE_DATE)  "MAX_DATE"
    ,UPPER(RETAIL)  "SHOP"
FROM PRODUCTS
GROUP BY UPPER(RETAIL)

the results are something like this

MAX_DATE   SHOP
2022-09-27 SHOP1
2022-08-01 SHOP2

I am looking for

2nd_MAX_DATE MAX_DATE   SHOP
2022-08-27   2022-09-27 SHOP1
2022-07-01   2022-08-01 SHOP2

I tried something with where clause WHERE FILE_DATE < ( SELECT MAX(FILE_DATE) FROM "PRODUCTS" GROUP BY UPPER(RETAILER)) but this isn't working

Answer 1

One way is to use a cross join.

Here's a full sample roughly altered to your schema using SQL Server syntax.

CREATE TABLE Products (
  Id INT PRIMARY KEY, 
  Retail VARCHAR(100), 
  FileDate DATETIME
);

INSERT INTO Products (Id, Retail, FileDate)
VALUES (1, 'shop 1', '2022-09-01'), 
       (2, 'shop 1', '2022-09-01'),
       (3, 'shop 1', '2022-09-01'),
       (4, 'shop 2', '2022-09-01'),
       (5, 'shop 2', '2022-09-01'),
       (6, 'shop 2', '2022-09-30'),
       (7, 'shop 3', '2022-09-01'),
       (8, 'shop 3', '2022-09-01'),
       (9, 'shop 3', '2022-09-20');

SELECT DISTINCT
    MAX(p1.FileDate) "MAX_DATE",
    UPPER(p1.Retail) "SHOP"
FROM Products p1
    CROSS JOIN Products p2
WHERE
    p1.FileDate > p2.FileDate
GROUP BY 
    p1.Retail,
    p2.Retail

Output

2022-09-30|SHOP 2
2022-09-20|SHOP 3

Answer 2

As you want the latest two file_dates for every shop, you can use WINDOW function

WITH CTE as(
SELECT FILE_DATE  
    ,UPPER(RETAIL)  "SHOP"
    , ROW_NUMBER() OVER(PARTITION BY UPPER(RETAIL) ORDER BY FILE_DATE DESC) rn
FROM PRODUCTS
)
SELECT "SHOP",MIN(FILE_DATE) second_date, MAX(FILE_DATE) first_date
FROM CTE 
WHERE rn < 3 
GROUP BY "SHOP"

Answer 3

create or replace TABLE SNOWPARK_QUICKSTART.TELCO.Products ( ID INT, FileDate TIMESTAMP, Retail VARCHAR(16777216) );

INSERT INTO Products (Id, Retail, FileDate)
VALUES (1, 'shop 1', '2022-09-01'), 
   (2, 'shop 1', '2022-09-01'),
   (3, 'shop 1', '2022-09-01'),
   (4, 'shop 2', '2022-09-01'),
   (5, 'shop 2', '2022-09-01'),
   (6, 'shop 2', '2022-09-30'),
   (7, 'shop 3', '2022-09-01'),
   (8, 'shop 3', '2022-09-01'),
   (9, 'shop 3', '2022-09-20');


SELECT RETAIL
      ,FILEDATE
      ,IFF(RANK()OVER(PARTITION BY RETAIL ORDER BY FILEDATE DESC)=2,'SECOND MAX DATE','MAX DATE') DAY_DESC  
FROM 
    Products 
GROUP BY 
    RETAIL,FILEDATE
QUALIFY 
    RANK()OVER(PARTITION BY RETAIL ORDER BY FILEDATE DESC)<3 

Answer 4

Using the data provided PeteGo as a CTE:

with Products (Id, Retail, FileDate) as 
(
    select * from values
        (1, 'shop 1', '2022-09-01'::date), 
        (2, 'shop 1', '2022-09-01'::date),
        (3, 'shop 1', '2022-09-01'::date),
        (4, 'shop 2', '2022-09-01'::date),
        (5, 'shop 2', '2022-09-01'::date),
        (6, 'shop 2', '2022-09-30'::date),
        (7, 'shop 3', '2022-09-01'::date),
        (8, 'shop 3', '2022-09-01'::date),
        (9, 'shop 3', '2022-09-20'::date)
)

you can use the window function NTH_VALUE and then combine with DISTINCT to de-dup:

select distinct
    Retail
    ,nth_value(FileDate, 1) over(partition by retail order by filedate desc) as "1st_MAX_DATE"
    ,nth_value(FileDate, 2) over(partition by retail order by filedate desc) as "2nd_MAX_DATE"
from products

gives:

RETAIL	1st_MAX_DATE	2nd_MAX_DATE
shop 1	2022-09-01	2022-09-01
shop 2	2022-09-30	2022-09-01
shop 3	2022-09-20	2022-09-01

But you can see the two values of 2022-09-01 for shop 1 are getting picked.

and can be shown if you also pick the id's:

select distinct
    Retail
    ,nth_value(FileDate, 1) over(partition by retail order by filedate, id desc) as "1st_MAX_DATE"
    ,nth_value(FileDate, 2) over(partition by retail order by filedate, id desc) as "2nd_MAX_DATE"
    ,nth_value(id, 1) over(partition by retail order by filedate, id desc) as "1st_id"
    ,nth_value(id, 2) over(partition by retail order by filedate, id desc) as "2nd_id"
from products

RETAIL	1st_MAX_DATE	2nd_MAX_DATE	1st_id	2nd_id
shop 1	2022-09-01	2022-09-01	3	2
shop 2	2022-09-01	2022-09-01	5	4
shop 3	2022-09-01	2022-09-01	8	7

you can therefore de-dup the shops/dates:

select distinct
    Retail
    ,nth_value(FileDate, 1) over(partition by retail order by filedate desc) as "1st_MAX_DATE"
    ,nth_value(FileDate, 2) over(partition by retail order by filedate desc) as "2nd_MAX_DATE"
from (
    select distinct Retail, FileDate from products     
)

now gives a null as I originally expected:

RETAIL	1st_MAX_DATE	2nd_MAX_DATE
shop 1	2022-09-01	null
shop 2	2022-09-30	2022-09-01
shop 3	2022-09-20	2022-09-01