Constructing the SQL query below - sql

Question

GOALS (~1700 rows)
YEAR COUNTRY NAME NUM_GOALS
-------------------------------------------
2018 England Harry Kane 6
2018 France Antoine Griezmann 4
2014 Argentina Lionel Messi 4
2014 Brazil Fred 1
2010 Germany Thomas Muller 5
2010 Japan Shinji Okazaki 1
1992 England Gary Linekar 6
CHAMPIONS (~500 rows)
YEAR COUNTRY NAME ROLE
-------------------------------------------------
2018 France Didier Deschamps Manager
2018 France Hugo Lloris Goalkeeper
2018 France Paul Pogba Midfielder
2014 Germany Joachim Loew Manager
2014 Germany Mesut Ozil Midfielder
2014 Germany Miroslav Klose Forward
2002 Brazil Da Silva Midfielder
1994 Brazil Da Silva Midfielder
1998 France Didier Deschamps Midfielder
Write a query showing all world cup winning players who have never scored a goal.
What I am unsure about is whether to use a join for this and whether there is a need to specify and ID's if a join is to be used.
I'd be grateful for extra clarification and help with this, or if my query needs any tweaking.
What I have tried:
This is what I came up with:
SELECT GOALS.NAME
FROM GOALS
INNER JOIN CHAMPIONS ON CHAMPIONS.COUNTRY = GOALS.NAME
WHERE GOALS.NUM_GOALS = 0;

Answer 1

Problems with your query:
the join condition does not look right
even if it was, it searches for players that had at least one world cup without scoring a goal - which is different from those that never scored a goal
You could use not exists:
select c.*
from champions c
where not exists (
select 1
from goals g
where g.country = c.country and g.name = c.name and g.num_goals > 0
)
This assumes that (country, name) tuples do identify a player.
On the other hand, if you want players that won a world cup without scoring a goal in that particular event, then you can either add a correlation condition on year, or use a straight join:
select c.*
from champions c
inner join goals g
on g.country = c.country
and g.name = c.name
and g.year = c.year
where g.num_goals = 0

Answer 2

Your ON condition is comparing CHAMPIONS.COUNTRY = GOALS.NAME, which is not a good comparison for joining these two tables. I would suggest doing this:
SELECT
GOALS.NAME
FROM
GOALS
INNER JOIN
CHAMPIONS
ON
CHAMPIONS.COUNTRY = GOALS.COUNTRY
WHERE
GOALS.NUM_GOALS = 0;