SQL for Analytics

5 questions. Use Show Answer, then slide right (or use Next) to continue.

Card 1 of 5

Question 1 SQL Logical Execution Order

Question 2 Difference between WHERE and HAVING

Question 3 Deduplicate to latest row per key

SELECT *
FROM (
  SELECT *,
         ROW_NUMBER() OVER (
           PARTITION BY key_col
           ORDER BY ts DESC
         ) AS rn
  FROM table
) t
WHERE rn = 1;

Question 4 Handle NULL safely in aggregation

SELECT key_col,
       COALESCE(SUM(amount), 0) AS total_amount
FROM table
GROUP BY key_col;

Question 5 Basic SQL structure template

SELECT columns
FROM table
JOIN other_table ON condition
WHERE condition
GROUP BY columns
HAVING aggregate_condition
ORDER BY column DESC
LIMIT 10;

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