xd-deng / sql-exercise

Practice with "Real" SQL Problems

SQL-exercise

Schemas, Questions & Solutions for SQL Exercising

Introduction

The schemas and questions are

[1] from Wikibook SQL Exercises [https://en.wikibooks.org/wiki/SQL_Exercises]. Solutions are from both this Wikibook and me (exercise 1-8). I also added some questions by myself.

or

[2] given by me using some practical examples I encountered (exercise 9-10).

Repository Structure

The repo structure is like below:

SQL-exercise
└───SQL_exercise_1
└───......
└───SQL_exercise_*
    │   *_schema_figure.png
    │   *_build_schema.sql
    │   *_questions_and_solutions.sql

└───......

License

Please note this repostory is under the Creative Commons Attribution-ShareAlike License[https://creativecommons.org/licenses/by-sa/3.0/].

sql-exercise's Issues

The answer of 5.5 is wrong

The correct answer is

maybe there is something with -- 1.16

it should be :
select p.name,m.name,p.price from products p join manufacturers m on p.manufacturer = m.code where p.price in (
select min(a.price)
from Manufacturers b join Products a
on a.Manufacturer = b.code
group by b.name);
Your answer always showes the wrong product name to match the price.

Reorder some things

I saw this repo and it's great how much exercises are.

It would be great what the exercises are separated from solutions.

If you accept pull request, I offer myself to do that work.

Better solution for Question no 1.16 in 1_questions_and_solutions.sql (SQL_exercise_01).

I have a better solution for Question 1.16 in SQL_exercise_01 which can solve the query in just 2 lines.

My solution:

select b.name, a.price, a.name
from products a join manufacturers b on (a.Manufacturer= b.code )
where a.price in (select max(price) as p from products group by manufacturer order by max(price) );

Current solution:

select max_price_mapping.name as manu_name, max_price_mapping.price, products_with_manu_name.name as product_name
from
(SELECT Manufacturers.Name, MAX(Price) price
FROM Products, Manufacturers
WHERE Manufacturer = Manufacturers.Code
GROUP BY Manufacturers.Name)
as max_price_mapping
left join
(select products.*, manufacturers.name manu_name
from products join manufacturers
on (products.manufacturer = manufacturers.code))
as products_with_manu_name
on
(max_price_mapping.name = products_with_manu_name.manu_name
and
max_price_mapping.price = products_with_manu_name.price);

Write a query that returns only the first and last name of employees whose title is IT.

exercise6and7 is too easy,too less

As the title.
exercise6and7 is too easy,too less

Write a query that returns only the first and last name of employees whose title is CPA.

Solutions for Exercise 8

Hi,

These are way helpful exercises. Thank you so much.
Can you please upload the solutions for Exercise 8. I couldn't find one !

Thanks.

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