Turn messy exports into answers in minutes.

SELECT
  customer_id,
  COUNT(*) AS cnt
FROM customers
GROUP BY 1
HAVING COUNT(*) > 1
ORDER BY cnt DESC
LIMIT 50;

SELECT
  c.customer_id,
  c.name,
  SUM(t.amount) AS total_spend,
  COUNT(*) AS txn_count
FROM customers c
JOIN transactions t
  ON t.customer_id = c.customer_id
GROUP BY 1,2
ORDER BY total_spend DESC
LIMIT 25;

SELECT
  COUNT(*) AS rows_total,
  SUM(CASE WHEN customer_id IS NULL THEN 1 ELSE 0 END) AS missing_customer_id,
  SUM(CASE WHEN amount IS NULL THEN 1 ELSE 0 END) AS missing_amount,
  SUM(CASE WHEN amount <= 0 THEN 1 ELSE 0 END) AS non_positive_amount
FROM transactions;

WITH tx AS (
  SELECT
    customer_id,
    SUM(amount) AS tx_total
  FROM transactions
  GROUP BY 1
),
pay AS (
  SELECT
    customer_id,
    SUM(amount) AS pay_total
  FROM payments
  GROUP BY 1
)
SELECT
  COALESCE(tx.customer_id, pay.customer_id) AS customer_id,
  COALESCE(tx_total, 0) AS tx_total,
  COALESCE(pay_total, 0) AS pay_total,
  (COALESCE(pay_total, 0) - COALESCE(tx_total, 0)) AS diff
FROM tx
FULL OUTER JOIN pay
  ON tx.customer_id = pay.customer_id
ORDER BY ABS(diff) DESC
LIMIT 50;