Count Distinct Window Function with Groupby - sql

Question

I have a table that contains a user's name, market, and purchase_id. I'm trying to use a window function in SnowSql without a subquery to count the distinct number of purchases a user bought as well as the total number of unique purchases for the market.
Initial Table
User
Market
Purchase_ID
John Smith
NYC
1
John Smith
NYC
2
Bob Miller
NYC
2
Bob Miller
NYC
4
Tim Wilson
NYC
3
The desired result would look like this:
User
Purchases
Unique Market Purchases
John Smith
2
4
Bob Miller
2
4
Tim Wilson
1
4
The query I've been attempting without a subquery looks like the below but receives an error with the groupby.
SELECT
user,
COUNT(DISTINCT purchase_id),
COUNT(DISTINCT purchase_id) OVER (partition by market)
FROM table
GROUP BY 1
Appreciate any assistance with this. Thanks!

Answer 1

This might work , you could wrangle to get into the format you're after but it produces the answer without subquery.
Uses the awesome GROUPING SETS which allows multiple group-by clauses in a single statement - the exact error you were hitting :-).
Awesome question!
SELECT
COUNT(DISTINCT PURCHASE_ID)
, USER_NAME
, MARKET
FROM
CTE
GROUP BY
GROUPING SETS (USER_NAME, MARKET);
Copy|Paste|Run
WITH CTE AS (SELECT 'JOHN SMITH' USER_NAME, 'NYC' MARKET, 1
PURCHASE_ID
UNION SELECT 'JOHN SMITH' USER_NAME, 'NYC' MARKET, 2 PURCHASE_ID
UNION SELECT 'BOB MILLER' USER_NAME, 'NYC' MARKET, 2 PURCHASE_ID
UNION SELECT 'BOB MILLER' USER_NAME, 'NYC' MARKET, 4 PURCHASE_ID
UNION SELECT 'TIM WILSON' USER_NAME, 'NYC' MARKET, 3 PURCHASE_ID)
SELECT
COUNT(DISTINCT PURCHASE_ID)
, USER_NAME
, MARKET
FROM
CTE
GROUP BY
GROUPING SETS (USER_NAME, MARKET);

Answer 2

I don't think you can do this simply as an aggregation. But you can get the answer like this:
SELECT user,
SUM( (seqnum = 1)::INT ) as purchases,
SUM(SUM( (seqnum = 1)::INT )) OVER (PARTITION BY market) as market_purchases
FROM (SELECT t.*,
ROW_NUMBER() OVER (PARTITION BY purchase_id ORDER BY purchase_id) as seqnum
FROM table t
) t
GROUP BY 1

Answer 3

DISTTNCT in a window function is not allowed, so you need to use the subquery
CREATE TABLE table1
(`User` varchar(10), `Market` varchar(3), `Purchase_ID` int)
;
INSERT INTO table1
(`User`, `Market`, `Purchase_ID`)
VALUES
('John Smith', 'NYC', 1),
('John Smith', 'NYC', 2),
('Bob Miller', 'NYC', 2),
('Bob Miller', 'NYC', 4),
('Tim Wilson', 'NYC', 3)
;
SELECT
user,
COUNT(DISTINCT purchase_id)
,MAX((SELECT COUNT(DISTINCT purchase_id) FROM table1 WHERE `Market` = t1.`Market` )) bymarkte
FROM table1 t1
GROUP BY 1
user | COUNT(DISTINCT purchase_id) | bymarkte
:--------- | --------------------------: | -------:
Bob Miller | 2 | 4
John Smith | 2 | 4
Tim Wilson | 1 | 4
SELECT
user,
COUNT(DISTINCT purchase_id)
,MAX(countr) bymarkte
FROM table1 t1
INNER JOIN (SELECT `Market`,COUNT(DISTINCT purchase_id) countr FROM table1 GROUP BY `Market` ) ta ON t1.`Market` = ta.`Market`
GROUP BY 1
user | COUNT(DISTINCT purchase_id) | bymarkte
:--------- | --------------------------: | -------:
Bob Miller | 2 | 4
John Smith | 2 | 4
Tim Wilson | 1 | 4
db<>fiddle here