Find the customers and other metrics based on the purchase frequency new & repeat - sql

Question

I am trying to find the customer count and sales by the type of customer (New and Returning) and the number of times they have purchased.
txn_date Customer_ID Transaction_Number Sales Reference(not in the SQL table) customer type (not in the sql table)
1/2/2019 1 12345 $10 Second Purchase SLS Repeat
4/3/2018 1 65890 $20 First Purchase SLS Repeat
3/22/2019 3 64453 $30 First Purchase SLS new
4/3/2019 4 88567 $20 First Purchase SLS new
5/21/2019 4 85446 $15 Second Purchase SLS new
1/23/2018 5 89464 $40 First Purchase SLS Repeat
4/3/2019 5 99674 $30 Second Purchase SLS Repeat
4/3/2019 6 32224 $20 Second Purchase SLS Repeat
1/23/2018 6 46466 $30 First Purchase SLS Repeat
1/20/2018 7 56558 $30 First Purchase SLS new
I am using the below code to get the aggregate sales and customer count for the total customers:
select seqnum, count(distinct customer_id), sum(sales) from (
select co.*,
row_number() over (partition by customer_id order by txn_date) as seqnum
from somya co)
group by seqnum
order by seqnum;
I want to get the same data by the customer type:
for example for the new customers my result should show:
New Customers Customer_Count Sum(Sales)
1st Purchase 3 $80
2nd Purchase 1 $15
Returning Customers Customer_Count Sum(Sales)
1st Purchase 3 $90
2nd Purchase 3 $60
I am trying the below query to get the data for new and repeat customers:
New Customers:
select seqnum, count(distinct customer_id), sum(sales)
from (
select co.*,
row_number() over (partition by customer_id order by trunc(txn_date)) as seqnum,
MIN (TRUNC (TXN_DATE)) OVER (PARTITION BY customer_id) as MIN_TXN_DATE
from somya co
)
where MIN_TXN_DATE between '01-JAN-19' and '31-DEC-19'
group by seqnum
order by seqnum asc;
Returning Customers:
select seqnum, count(distinct customer_id), sum(sales)
from (
select co.*,
row_number() over (partition by customer_id order by trunc(txn_date)) as seqnum,
MIN (TRUNC (TXN_DATE)) OVER (PARTITION BY customer_id) as MIN_TXN_DATE
from somya co
)
where MIN_TXN_DATE <'01-JAN-19'
group by seqnum
order by seqnum asc;
I am not able to figure out what is wrong with my query or if there is a problem with my logic.
This is just a sample data, I have transactions from all the years in my data base so I need to narrow the transaction date in the query but as soon as I narrowing down the data using the transaction date the repeat customer query doesnt give me anything and the new customer query gives me the total customer for that period.

Answer 1

If I understand correctly, you need to know the first time someone becomes a customer. And then use this:
select (case when first_year < 2019 then 'returning' else 'new' end) as custtype,
seqnum, count(*), sum(sales)
from (select co.*,
row_number() over (partition by customer_id, extract(year from txn_date) order by txn_date) as seqnum,
min(extract(year from txn_date)) over (partition by customer_id) as first_year
from somya co
) s
where txn_date >= date '2019-01-01' and
txn_date < date '2020-01-01'
group by (case when first_year < 2019 then 'returning' else 'new' end),
seqnum
order by custtype, seqnum;

Answer 2

You can categorize your sales data to assign a customer type and a purchase sequence using windowing functions, like this:
SELECT sd.txn_date,
sd.customer_id,
sd.transaction_number,
sd.sales,
case when min(txn_date) over ( partition by customer_id ) < DATE '2019-01-01'
AND max(txn_date) OVER ( partition by customer_id ) >= DATE '2019-01-01'
THEN 'Repeat'
ELSE 'New' END customer_type,
row_number() over ( partition by customer_id order by txn_date) purchase_sequence
FROM sales_data sd
+-----------+-------------+--------------------+-------+---------------+-------------------+
| TXN_DATE | CUSTOMER_ID | TRANSACTION_NUMBER | SALES | CUSTOMER_TYPE | PURCHASE_SEQUENCE |
+-----------+-------------+--------------------+-------+---------------+-------------------+
| 03-APR-18 | 1 | 65890 | 20 | Repeat | 1 |
| 02-JAN-19 | 1 | 12345 | 10 | Repeat | 2 |
| 22-MAR-19 | 3 | 64453 | 30 | New | 1 |
| 03-APR-19 | 4 | 88567 | 20 | New | 1 |
| 21-MAY-19 | 4 | 85446 | 15 | New | 2 |
| 23-JAN-18 | 5 | 89464 | 40 | Repeat | 1 |
| 03-APR-19 | 5 | 99674 | 30 | Repeat | 2 |
| 23-JAN-18 | 6 | 46466 | 30 | Repeat | 1 |
| 03-APR-19 | 6 | 32224 | 20 | Repeat | 2 |
| 20-JAN-18 | 7 | 56558 | 30 | New | 1 |
+-----------+-------------+--------------------+-------+---------------+-------------------+
Then, you can wrap that in a common table expression (aka "WITH" clause) and summarize by the customer type and purchase sequence:
WITH categorized_sales_data AS (
SELECT sd.txn_date,
sd.customer_id,
sd.transaction_number,
sd.sales,
case when min(txn_date) over ( partition by customer_id ) < DATE '2019-01-01' AND max(txn_date) OVER ( partition by customer_id ) >= DATE '2019-01-01' THEN 'Repeat' ELSE 'New' END customer_type,
row_number() over ( partition by customer_id order by txn_date) purchase_sequence
FROM sales_data sd)
SELECT customer_type, purchase_sequence, count(*), sum(sales)
FROM categorized_sales_data
group by customer_type, purchase_sequence
order by customer_type, purchase_sequence
+---------------+-------------------+----------+------------+
| CUSTOMER_TYPE | PURCHASE_SEQUENCE | COUNT(*) | SUM(SALES) |
+---------------+-------------------+----------+------------+
| New | 1 | 3 | 80 |
| New | 2 | 1 | 15 |
| Repeat | 1 | 3 | 90 |
| Repeat | 2 | 3 | 60 |
+---------------+-------------------+----------+------------+
Here's a full SQL with test data:
with sales_data (txn_date, Customer_ID, Transaction_Number, Sales ) as (
SELECT TO_DATE('1/2/2019','MM/DD/YYYY'), 1, 12345, 10 FROM DUAL UNION ALL
SELECT TO_DATE('4/3/2018','MM/DD/YYYY'), 1, 65890, 20 FROM DUAL UNION ALL
SELECT TO_DATE('3/22/2019','MM/DD/YYYY'), 3, 64453, 30 FROM DUAL UNION ALL
SELECT TO_DATE('4/3/2019','MM/DD/YYYY'), 4, 88567, 20 FROM DUAL UNION ALL
SELECT TO_DATE('5/21/2019','MM/DD/YYYY'), 4, 85446, 15 FROM DUAL UNION ALL
SELECT TO_DATE('1/23/2018','MM/DD/YYYY'), 5, 89464, 40 FROM DUAL UNION ALL
SELECT TO_DATE('4/3/2019','MM/DD/YYYY'), 5, 99674, 30 FROM DUAL UNION ALL
SELECT TO_DATE('4/3/2019','MM/DD/YYYY'), 6, 32224, 20 FROM DUAL UNION ALL
SELECT TO_DATE('1/23/2018','MM/DD/YYYY'), 6, 46466, 30 FROM DUAL UNION ALL
SELECT TO_DATE('1/20/2018','MM/DD/YYYY'), 7, 56558, 30 FROM DUAL ),
-- Query starts here
/* WITH */ categorized_sales_data AS (
SELECT sd.txn_date,
sd.customer_id,
sd.transaction_number,
sd.sales,
case when min(txn_date) over ( partition by customer_id ) < DATE '2019-01-01' AND max(txn_date) OVER ( partition by customer_id ) >= DATE '2019-01-01' THEN 'Repeat' ELSE 'New' END customer_type,
row_number() over ( partition by customer_id order by txn_date) purchase_sequence
FROM sales_data sd)
SELECT customer_type, purchase_sequence, count(*), sum(sales)
FROM categorized_sales_data
group by customer_type, purchase_sequence
order by customer_type, purchase_sequence
Response to comment from OP
all the customers whose first purchase date is in 2019 would be a new customer. Any customer who has transacted in 2019 but their first purchase date is before 2019 would be a repeat customer
So, change
case when min(txn_date) over ( partition by customer_id ) < DATE '2019-01-01'
AND max(txn_date) OVER ( partition by customer_id ) >= DATE '2019-01-01'
THEN 'Repeat' ELSE 'New' END customer_type
to
case when min(txn_date) over ( partition by customer_id )
BETWEEN DATE '2019-01-01' AND DATE '2020-01-01' - INTERVAL '1' SECOND
THEN 'New' ELSE 'Repeat' END customer_type
i.e., if and only if a customer's first purchase was in 2019 then they are "new".