How to use GROUP BY and JOIN in a SQL Statement? - sql

Question

I have two tables called "Player" and "Country":
Player
Person Goals Country
------- ----- -------
Pogba 1 France
Pavard 1 France
Griezmann 2 France
Neymar 3 Brazil
Silva 2 Brazil
Country
Name Continent
------- --------------
France Europe
Brazil South America
I want to show the sum of goals for each country and display the country name, continent, and total goals
So, I would like my output to look like this:
Country Continent Goals
------- ------------- ------
France Europe 4
Brazil South America 5
I can display Country & Continent together and Country & Goals together but I can't do all three.
Here is what I tried:
SELECT Country.Name, Country.Continent, SUM(Player.Goals)
FROM Player
INNER JOIN Country ON Player.Country = Country.Name
GROUP BY Player.Country;
Maybe I'm over simplifying it? I just don't know how I can get the desired result.

Answer 1

Try the below - add Country.Continent to group by too
SELECT Country.Name, Country.Continent, SUM(Player.Goals)
FROM Player
INNER JOIN Country ON Player.Country = Country.Name
GROUP BY Country.Name, Country.Continent

Answer 2

SELECT Country.Continent, Player.Country, SUM(Player.Goals)
FROM Player
INNER JOIN Country ON Player.Country = Country.Name
GROUP BY Country.Continent, Player.Country

Answer 3

try this;
SELECT Country.Name, Country.Continent, SUM(Player.Goals) as Goals
FROM Player
INNER JOIN Country ON Player.Country = Country.Name
GROUP BY Country.Name, Country.Continent;

Answer 4

Although adding continent to the GROUP BY is definitely one solution, there are others.
First, you can use an aggregation function on continent:
SELECT c.Name, MAX(c.Continent) as Continent, SUM(p.Goals)
FROM Player p JOIN
Country c
ON p.Country = c.Name
GROUP BY c.Name;
Or, you can use a correlated subquery:
SELECT c.*,
(SELECT SUM(p.Goals)
FROM Player p
WHERE p.Country = c.Name
) as goals
FROM Country c;
Note that both of these include table aliases, which make the query easier to write and read.
The advantage of the last version is that it avoids an aggregation in the outer query and also it allows you to easily choose as many columns from Country as you like. It can also take advantage of an index on Player(Country), if available -- although that is irrelevant on smaller amounts of data.