SQL Query to fetch the latest payment method and invoice date - sql

Question

There are four tables
First - Customer
Second - Invoice
Third - Supplier
Fourth - Supplier_Remit
Tables details are mentioned below
Customer_id
Customer_Account_number
Customer_Status
Supplier_id
Supplier_Remit_id
1
1501
Active
11
111
2
1502
Inactive
12
112
3
1503
Active
13
113
4
1504
Active
14
114
5
1505
Inactive
15
115
Invoice_Date
Invoice_Amount
Invoice_Number
Payment Method
Customer_id
01/01/2023
100
1000001
Cash
1
12/01/2022
150
1000002
Credit Card
1
11/09/2022
200
1000003
Credit Card
1
12/09/2022
300
1000004
Cash
2
04/15/2022
1000
1000005
Cash
2
04/15/2022
1000
1000006
Credit Card
3
10/31/2022
250
1000007
Cash
4
10/25/2022
250
1000008
Cash
4
09/20/2022
130
1000009
Credit Card
5
05/20/2022
120
10000010
Credit Card
5
Supplier_Name
Supplier_id
ABC
11
ACCC
12
ADEF
13
AJKL
14
AFLR
15
City
Country
Supplier_Remit_id
Supplier_id
Boston
US
111
11
Oak
US
112
12
Albany
US
113
13
Madison
US
114
14
Los Ang
US
115
15
I need help in finding the most recent payment method, most recent invoice amount, no of count of invoices missing for current year (2023) and no of count of invoices missing for previous year(2022)
I have written query to find first few columns but unable to write further to get the above mentioned details
select c.customer_id,c.customer_account_number,c.customer_status,sr.country,max(i.invoice_date) as Latest receieved_Invoice_date
from
customer c,
invoice i,
supplier s,
supplier_Remit sr
where
c.customer_status='Active' and
sr.supplier_id=s.supplier_id and
c.supplier_remit_id=sr.supplier_remit_id and
c.customer_id=i.customer_id
group by
c.customer_id,c.customer_account_number,c.customer_status,sr.country;
My expected output would be as below
Customer_id
Cust_Acct_Num
Cust_Status
Country
Last_Inv_Rec_Date
1
1501
Active
US
01/01/2023
3
1503
Active
US
04/15/2022
4
1504
Active
US
10/31/2022
Latest_Paym_Method
Lastest_Inv_Amt
Count of Missing Inv for Curr Yr
Cash
100
0
Credit card
1000
1
Cash
250
1
Count of Missing Invoices for Prev Year
10
11
11

Answer 1

You can use MAX(...) KEEP (DENSE_RANK LAST ORDER BY invoice_date) to get values for the latest invoice and conditional aggregation to count the number of months where there are invoices and then subtract from the total number of months to find the missing invoices:
SELECT c.Customer_id,
c.Customer_Account_number,
c.Customer_Status,
r.country,
i.last_invoice_date,
i.latest_payment_method,
i.latest_invoice_amount,
EXTRACT(MONTH FROM SYSDATE) - COALESCE(i.missing_invoices_this_year, 0)
AS missing_invoices_this_year,
12 - COALESCE(i.missing_invoices_last_year, 0)
AS missing_invoices_last_year
FROM customer c
INNER JOIN supplier_remit r
ON (c.supplier_id = r.supplier_id)
LEFT OUTER JOIN (
SELECT customer_id,
MAX(invoice_date) AS last_invoice_date,
MAX(payment_method) KEEP (DENSE_RANK LAST ORDER BY invoice_date)
AS latest_payment_method,
MAX(invoice_amount) KEEP (DENSE_RANK LAST ORDER BY invoice_date)
AS latest_invoice_amount,
COUNT(
DISTINCT
CASE
WHEN invoice_date < SYSDATE
AND invoice_date >= TRUNC(SYSDATE, 'YY')
THEN TRUNC(invoice_date, 'MM')
END
) AS missing_invoices_this_year,
COUNT(
DISTINCT
CASE
WHEN invoice_date < TRUNC(SYSDATE, 'YY')
AND invoice_date >= ADD_MONTHS(TRUNC(SYSDATE, 'YY'), -12)
THEN TRUNC(invoice_date, 'MM')
END
) AS missing_invoices_last_year
FROM invoice
GROUP BY customer_id
) i
ON (c.customer_id = i.customer_id)
WHERE c.customer_status = 'Active';
Which, for the sample data:
CREATE TABLE customer (Customer_id, Customer_Account_number, Customer_Status, Supplier_id, Supplier_Remit_id) AS
SELECT 1, 1501, 'Active', 11, 111 FROM DUAL UNION ALL
SELECT 2, 1502, 'Inactive', 12, 112 FROM DUAL UNION ALL
SELECT 3, 1503, 'Active', 13, 113 FROM DUAL UNION ALL
SELECT 4, 1504, 'Active', 14, 114 FROM DUAL UNION ALL
SELECT 5, 1505, 'Inactive', 15, 115 FROM DUAL;
CREATE TABLE invoice (Invoice_Date, Invoice_Amount, Invoice_Number, Payment_Method, Customer_id) AS
SELECT DATE '2023-01-01', 100, 1000001, 'Cash', 1 FROM DUAL UNION ALL
SELECT DATE '2022-12-01', 150, 1000002, 'Credit Card', 1 FROM DUAL UNION ALL
SELECT DATE '2022-11-09', 200, 1000003, 'Credit Card', 1 FROM DUAL UNION ALL
SELECT DATE '2022-12-09', 300, 1000004, 'Cash', 2 FROM DUAL UNION ALL
SELECT DATE '2022-04-15', 1000, 1000005, 'Cash', 2 FROM DUAL UNION ALL
SELECT DATE '2022-04-15', 1000, 1000006, 'Credit Card', 3 FROM DUAL UNION ALL
SELECT DATE '2022-10-31', 250, 1000007, 'Cash', 4 FROM DUAL UNION ALL
SELECT DATE '2022-10-25', 250, 1000008, 'Cash', 4 FROM DUAL UNION ALL
SELECT DATE '2022-09-20', 130, 1000009, 'Credit Card', 5 FROM DUAL UNION ALL
SELECT DATE '2022-05-20', 120, 10000010, 'Credit Card', 5 FROM DUAL;
CREATE TABLE supplier (Supplier_Name, Supplier_id) AS
SELECT 'ABC', 11 FROM DUAL UNION ALL
SELECT 'ACCC', 12 FROM DUAL UNION ALL
SELECT 'ADEF', 13 FROM DUAL UNION ALL
SELECT 'AJKL', 14 FROM DUAL UNION ALL
SELECT 'AFLR', 15 FROM DUAL;
CREATE TABLE supplier_remit (City, Country, Supplier_Remit_id, Supplier_id) AS
SELECT 'Boston', 'US', 111, 11 FROM DUAL UNION ALL
SELECT 'Oak', 'US', 112, 12 FROM DUAL UNION ALL
SELECT 'Albany', 'US', 113, 13 FROM DUAL UNION ALL
SELECT 'Madison', 'US', 114, 14 FROM DUAL UNION ALL
SELECT 'Los Ang', 'US', 115, 15 FROM DUAL;
Outputs:
CUSTOMER_ID
CUSTOMER_ACCOUNT_NUMBER
CUSTOMER_STATUS
COUNTRY
LAST_INVOICE_DATE
LATEST_PAYMENT_METHOD
LATEST_INVOICE_AMOUNT
MISSING_INVOICES_THIS_YEAR
MISSING_INVOICES_LAST_YEAR
1
1501
Active
US
2023-01-01 00:00:00
Cash
100
0
10
3
1503
Active
US
2022-04-15 00:00:00
Credit Card
1000
1
11
4
1504
Active
US
2022-10-31 00:00:00
Cash
250
1
11
fiddle

Answer 2

In order to find what's missing, you have to first define what should be there, so you need to create a calendar of every month. Then you can use outer joins to the invoice table to find where there aren't any records for that month for that customer. There are lots of ways to write SQL to do this. Here's one:
WITH months AS(SELECT /*+ MATERIALIZE */ *
FROM (SELECT 'Current' year,
ADD_MONTHS(TRUNC(SYSDATE,'YYYY'),ROWNUM-1) month_start
FROM [any table with at least 12 rows]
WHERE ROWNUM <= 12)
WHERE month_start < SYSDATE
UNION ALL
SELECT 'Previous' year,
ADD_MONTHS(TRUNC(ADD_MONTHS(SYSDATE,-12),'YYYY'),ROWNUM-1)
FROM [any table with at least 12 rows]
WHERE ROWNUM <= 12)
SELECT customer.*,
inv.invoice_amount most_recent_invoice_amount,
inv.payment_method most_recent_payment_method,
(SELECT COUNT(*)
FROM months,
invoice
WHERE months.year = 'Current'
AND months.month_start = TRUNC(invoice_date(+),'MM')
AND invoice.customer_id(+) = customer.customer_id
AND invoice.customer_id IS NULL) missed_current_year_months,
(SELECT COUNT(*)
FROM months,
invoice
WHERE months.year = 'Previous'
AND months.month_start = TRUNC(invoice_date(+),'MM')
AND invoice.customer_id(+) = customer.customer_id
AND invoice.customer_id IS NULL) missed_previous_year_months
FROM customer
OUTER APPLY (SELECT invoice_amount,
payment_method
FROM (SELECT invoice_amount,
payment_method,
ROW_NUMBER() OVER (ORDER BY invoice_date DESC) seq
FROM invoice
WHERE invoice.customer_id = customer.customer_id)
WHERE seq = 1) inv