How to Identify Users with Multiple Daily Payments on the Same Account Using SQL?

Using SQL to Find Users with Multiple Daily Payments on the Same Account

This guide demonstrates how to identify users who have made more than one payment on the same day, using the same account number, and with different ZIP codes. We'll use the PAYMENT table, containing user_id, account_no, zip, and date columns.

Initial SQL Query:

This query identifies users with multiple payments per day, per account:

SELECT
  user_id,
  COUNT(*) AS payment_count
FROM
  PAYMENT
GROUP BY
  account_no,
  user_id,
  date
HAVING
  COUNT(*) > 1;

This groups payments by account number, user ID, and date, then filters to show only groups with more than one payment.

Enhanced Query for Distinct ZIP Codes:

To ensure that only users with multiple payments and distinct ZIP codes are identified, we use a subquery:

SELECT
  user_id,
  account_no,
  date,
  COUNT(*) AS payment_count
FROM
  (SELECT DISTINCT
    user_id,
    account_no,
    zip,
    date
  FROM
    PAYMENT) AS distinct_payments
GROUP BY
  user_id,
  account_no,
  date
HAVING
  COUNT(*) > 1;

This subquery (distinct_payments) first selects unique combinations of user, account, ZIP code, and date. The main query then groups and filters this subset, guaranteeing that only records with multiple payments and distinct ZIP codes are returned. The AS distinct_payments clause assigns an alias to the subquery for clarity.

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