📊 AggregationintermediateCommonly used

How to use HAVING in SQL

Filter groups after aggregation — like WHERE but for GROUP BY results.

Filter groups by aggregate valueAll databases

SELECT
  country,
  COUNT(*) AS user_count
FROM users
GROUP BY country
HAVING COUNT(*) > 100;

HAVING filters AFTER aggregation. Returns only countries with more than 100 users.

When to use: Filtering based on an aggregate value like COUNT, SUM, AVG.

HAVING vs WHERE — key differenceAll databases

-- WHERE filters rows BEFORE grouping:
SELECT country, COUNT(*) AS count
FROM users
WHERE active = true          -- filter rows first
GROUP BY country
HAVING COUNT(*) > 50;        -- then filter groups

WHERE runs before GROUP BY (filters rows). HAVING runs after GROUP BY (filters groups). Use both together when needed.

HAVING with multiple conditionsAll databases

SELECT
  user_id,
  COUNT(*)   AS order_count,
  SUM(total) AS total_spent
FROM orders
GROUP BY user_id
HAVING COUNT(*) >= 5
   AND SUM(total) > 1000;

Find users who placed at least 5 orders AND spent more than $1000 total.

Find duplicates with HAVINGAll databases

SELECT email, COUNT(*) AS occurrences
FROM users
GROUP BY email
HAVING COUNT(*) > 1;

Classic pattern for finding duplicate values — group and filter for count > 1.

When to use: Data quality checks, finding duplicate records.

Common Mistakes

→Using HAVING instead of WHERE for row-level filters — HAVING is slower
→Confusing WHERE and HAVING: WHERE filters before grouping, HAVING filters after

Common Mistakes

Related Topics