DB Quacks SQL Tutorial · Chapter 6
Inception: We Need to Go Deeper
Dream architect duck approaches in dark glasses. We must go deeper! Find ducks older than average age, but I dont know the average! Use a query inside another query - nested intelligence!
Your task
Find all ducks from the ducks table whose age is greater than the average age of all ducks. You will be using a subquery to calculate the average age first.
Hint
You need to use a query inside another query - think about how to calculate the average first, then use that result.
Expected result
A table showing ducks whose age is above the average age.
Tables
duck_diaries (10 rows)
| column | type |
|---|---|
diary_id | BIGINT |
duck_id | BIGINT |
entry_date | DATE |
diary_text | VARCHAR |
mood | VARCHAR |
duck_surveys (5000 rows)
| column | type |
|---|---|
survey_id | BIGINT |
duck_id | BIGINT |
age | BIGINT |
favorite_food | VARCHAR |
favorite_pond | BIGINT |
swimming_rating | BIGINT |
migration_preference | VARCHAR |
social_behavior | VARCHAR |
health_status | VARCHAR |
activity_level | VARCHAR |
survey_date | DATE |
survey_location | BIGINT |
ducks (15 rows)
| column | type |
|---|---|
id | BIGINT |
name | VARCHAR |
age | BIGINT |
species | VARCHAR |
birth_date | DATE |
arrival_date | DATE |
ponds (3 rows)
| column | type |
|---|---|
pond_id | BIGINT |
pond_name | VARCHAR |
location_lat | DOUBLE |
location_lng | DOUBLE |
capacity | BIGINT |
features | VARCHAR[] |
amenities | VARCHAR[] |
Database: https://dbquacks.com/data/databases/tutorial.duckdb
This page as markdown: https://dbquacks.com/tutorial/29.md