✨ DB Nerdery Challenges Solutions I #54
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README.md
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| ```sql | ||
| SELECT c.name, count(s.name) | ||
| FROM states AS s | ||
| INNER JOIN countries AS c | ||
| ON s.country_id = c.id | ||
| group by c.name | ||
| ``` |
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nit: Use uppercase for keywords and consist identention
| ```sql | |
| SELECT c.name, count(s.name) | |
| FROM states AS s | |
| INNER JOIN countries AS c | |
| ON s.country_id = c.id | |
| group by c.name | |
| ``` | |
| ```sql | |
| SELECT | |
| c.name, | |
| COUNT(s.name) | |
| FROM | |
| states AS s | |
| INNER JOIN countries AS c ON s.country_id = c.id | |
| GROUP BY | |
| c.name``` |
README.md
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| ``` | ||
| Your query here | ||
| ```sql | ||
| SELECT c.name, count(s.name) |
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suggestion: on aggregated functions tend to use a alias that it actual represents the column
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Question: what is going to happened if state name is null?
| ``` | ||
| Your query here | ||
| ```sql | ||
| SELECT COUNT(*) AS employees_without_supervisors |
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Nice one using a meaning name for the alias
README.md
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| ```SQL | ||
| SELECT c.name, | ||
| o.address, | ||
| COUNT(e.id) AS count |
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nit: it is practically the same as not adding a alias, choose a better name
README.md
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| SELECT count(*) AS list_of_office | ||
| FROM offices AS o | ||
| INNER JOIN states AS s | ||
| ON o.state_id = s.id | ||
| WHERE s.name = 'Colorado' | ||
| AND s.country_id = (SELECT id FROM countries AS c WHERE name = 'United States'); |
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Suggestion: improve indentation on this query
README.md
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| INNER JOIN states AS s | ||
| ON o.state_id = s.id | ||
| WHERE s.name = 'Colorado' | ||
| AND s.country_id = (SELECT id FROM countries AS c WHERE name = 'United States'); |
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Why do you use a sub query here instead of using a inner join?
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I was not completely sure how to solve it, so I tried doing it in the first way that I realized worked. Now, I have a better understanding of how to use JOINS in queries, and it would be more readable to use an INNER JOIN instead of a subquery
README.md
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| (SELECT * | ||
| FROM office_count | ||
| WHERE count = (SELECT MAX(count) FROM office_count) | ||
| LIMIT 1) | ||
|
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You can also create more CTEs to improve this
README.md
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| (SELECT * | ||
| FROM office_count | ||
| WHERE count = (SELECT MAX(count) FROM office_count) |
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You're already operating a result to match with another result, it works but it can be hard to read, you can use an approach of sorting the office count table instead
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And the call is redundant because you're using two query calls against the same table without being fully necessary
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You’re alright. It could have been better to use ORDER BY instead of using this subquery selection
README.md
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| ) | ||
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| SELECT e.uuid, | ||
| e.first_name || ' ' || e.last_name AS full_name, |
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nit: IMO concat can be more readable instead of using this one
README.md
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| e2.first_name AS boss_name | ||
| FROM employees AS e | ||
| INNER JOIN offices_by_countries_with_states AS o ON e.office_id = o.office_id | ||
| LEFT JOIN employees AS e2 ON e.supervisor_id = e2.id |
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suggestion: e2 is not a descriptive alias you can use a descriptive one
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Nice job 👍🏻 |
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