How do I include duplicates? Tried HAVING - sql

Question

I am trying to learn SQL, and I am doing a project based on a provided database about past Superbowls. I wrote the below code to try to return a "yes" or "no" (to show I know how to use CASE) in a new column for teams that beat their opponents by more than 14 points. It worked, in a sense, but only returned each winning team once, AKA removed duplicates for teams that have won multiple times, but I want it to return all duplicates to show all games, HELP! I tried a HAVING clause, but I didn't really know what to put...
display which teams have beaten their opponents by >=14 points
I have Tried this below query:
SELECT Winner, Winner_Pts, Loser, Loser_Pts,Date,
CASE
WHEN (AVG(Winner_Pts-Loser_Pts) >= 14) THEN "yes"
ELSE "no"
END as "won_by_more_than_14"
FROM superbowls
GROUP BY Winner
ORDER BY Winner_Pts DESC

Answer 1

In your scenario, there is no need to aggregate your data in order to find teams that have beaten their opponents by >= 14 points.
If you remove your AVG function and GROUP BY aggregation, you will return teams that have won the super bowl (and more than once); otherwise, your CASE statement is correct.
SELECT Winner,
Winner_Pts,
Loser,
Loser_Pts,
Date,
CASE
WHEN (Winner_Pts-Loser_Pts) >= 14 THEN "Yes"
ELSE "No"
END AS "won_by_more_than_14"
FROM superbowls
ORDER BY Winner_Pts DESC
You can even add your CASE statement to a WHERE clause to only SELECT rows for teams than won by more than 14 points.
WHERE (CASE
WHEN (Winner_Pts-Loser_Pts) >= 14 THEN "Yes"
ELSE "No"
END) = "Yes"
Input Data:
ID
Number
Winner
Winner_Pts
Loser
Loser_Pts
Date
1
LVI
Rams
23
Bengals
20
2022-02-13 00:00:00
2
LV
Buccaneers
31
Chiefs
9
2021-02-07 00:00:00
3
LVI
Chiefs
31
49ers
20
2022-02-02 00:00:00
4
LII
Eagles
41
Patriots
33
2018-02-04 00:00:00
5
50
Broncos
24
Panthers
10
2016-02-07 00:00:00
6
XLVIII
Seahawks
43
Denver
8
2014-02-02 00:00:00
7
XXXIV
Rams
23
Titans
16
2000-01-30 00:00:00
8
LIII
Patriots
13
Rams
3
2019-02-03 00:00:00
9
LI
Patriots
34
Falcons
28
2017-02-05 00:00:00
Output Data:
Winner
Winner_Pts
Loser
Loser_Pts
Date
won_by_more_than_14
Seahawks
43
Denver
8
2014-02-02 00:00:00
Yes
Eagles
41
Patriots
33
2018-02-04 00:00:00
No
Patriots
34
Falcons
28
2017-02-05 00:00:00
No
Buccaneers
31
Chiefs
9
2021-02-07 00:00:00
Yes
Chiefs
31
49ers
20
2022-02-02 00:00:00
No
Broncos
24
Panthers
10
2016-02-07 00:00:00
Yes
Rams
23
Bengals
20
2022-02-13 00:00:00
No
Rams
23
Titans
16
2000-01-30 00:00:00
No
Patriots
13
Rams
3
2019-02-03 00:00:00
No
See Fiddle here.
Details:
Removing the AVG() function will get the results you want, but that doesn't mean AVG() isn't useful, especially for sports data. If you did want to aggregate your data, please see the following:
The AVG() function is used to find the average of values over records from a table. AVG() belongs to a class of functions known as aggregate functions. An aggregate function returns a single computed result over multiple rows:
Aggregate Function
Example Use Case
SUM()
Find the sum of points by team.
COUNT()
Find the number of bowls by each team.
MAX()
Find the highest point value by each team.
MIN()
Find the lowest point value by each team.
AVG()
Find the average points by team.
The SQL GROUP BY clause is used to group rows together. In most cases, a GROUP BY clause has one or more aggregate functions that calculate one or more metrics for the group.
Let's take this example here, I'm simply returning all Winners and their points:
SELECT
Winner,
Winner_Pts AS 'points'
FROM superbowls
ORDER BY Winner_Pts DESC
Winner
points
Seahawks
43
Eagles
41
Patriots
34
Buccaneers
31
Chiefs
31
Broncos
24
Rams
23
Rams
23
Patriots
13
Now let's aggregate it by Winner to find the average points:
SELECT
Winner,
ROUND(AVG(Winner_Pts)) AS 'avg_points'
FROM superbowls
GROUP BY Winner
ORDER BY ROUND(AVG(Winner_Pts)) DESC
Winner
avg_points
Seahawks
43
Eagles
41
Buccaneers
31
Chiefs
31
Broncos
24
Patriots
24
Rams
23
As you can see between the two queries above, the Rams and Patriots only have a single row (GROUPED BY Winner), and the average is:
(23+23)/2 = 23 (Rams)
(13+34)/2 = 23.5 - Rounded to 24 (Patriots)
(41)/1 = 41 (Eagles)
Source.
If you want to filter your data using GROUP BY, use HAVING. This is different from the WHERE clause because the GROUP BY clause runs after WHERE clauses which means that you can only use WHERE on “raw” data and not on aggregated values. You need to use HAVING on aggregated metrics.
The primary use of the HAVING operation is to filter aggregated data.
You can use it when you summarize your data with GROUP BY into new
metrics, and you want to select the results based on these new values.
Example:
Find teams with average winning points greater than 40:
SELECT
Winner,
ROUND(AVG(Winner_Pts)) AS 'avg_points'
FROM superbowls
GROUP BY Winner
HAVING ROUND(AVG(Winner_Pts)) > 40
ORDER BY ROUND(AVG(Winner_Pts)) DESC
Winner
avg_points
Seahawks
43
Eagles
41
Source.