How do I use count and group by as a condition for another table - sql

Question

So to preface, I'm a first-year comp sci student and we've only just started on SQL, so forgive me if the solution seems obvious.
We were given a database for Zoo, which has tables for Animals, Keepers, and a link entity (if that's the right word) for care roles, connecting the two.
(Schema below)
CREATE TABLE Animal (ID VARCHAR(6) PRIMARY KEY, Name VARCHAR(10), Species
VARCHAR(20),
Age SMALLINT, Sex VARCHAR(1), Weight SMALLINT, F_ID VARCHAR(6), M_ID
VARCHAR(6));
CREATE TABLE Keeper (Staff_ID VARCHAR(6) PRIMARY KEY, Keeper_Name
VARCHAR(20), Specialisation VARCHAR(20));
CREATE TABLE Care_Role (ID VARCHAR(6), Staff_ID VARCHAR(6), Role
VARCHAR(10), PRIMARY KEY (ID, Staff_ID));
Now the task we've been given is to work out which Keepers have been caring for more than 10 animals of the same species using the following data:
INSERT INTO Animal VALUES
('11', 'Horace', 'Marmoset', 99, 'M', 5, '2','1'),
('12', 'sghgdht', 'Marmoset', 42, 'M', 3, '2','1'),
('13', 'xgnyn', 'Marmoset', 37, 'F', 3, '1','11'),
('14', 'sbfdfbng', 'Marmoset', 12, 'F', 3, '1','11'),
('15', 'fdghd', 'Marmoset', 12, 'M', 3, '1','11'),
('16', 'Fred', 'Marmoset', 6, 'M', 3, '15','1'),
('17', 'Mary', 'Marmoset', 3, 'F', 3, '8','14'),
('18', 'Jane', 'Marmoset', 5, 'F', 3, '7','13'),
('19', 'dfgjtjt', 'Marmoset', 5, 'M', 3, '16','17'),
('20', 'Eric', 'Marmoset', 5, 'M', 3, '12','13'),
('21', 'tukyufyu', 'Marmoset', 5, 'M', 3, '12','73'),
('31', 'hgndghmd', 'Giraffe', 99, 'M', 5, '201','1'),
('32', 'sghgdht', 'Giraffe', 42, 'M', 3, '201','1'),
('33', 'xgnyn', 'Giraffe', 37, 'F', 3, '111','1'),
('34', 'sbfdfbng', 'Giraffe', 12, 'F', 3, '111','1'),
('35', 'fdghd', 'Giraffe', 12, 'M', 3, '111','6'),
('36', 'Fred', 'Lion', 6, 'M', 3, '151','111'),
('37', 'Mary', 'Lion', 3, 'F', 3, '81','114'),
('38', 'Jane', 'Lion', 5, 'F', 3, '71','113'),
('39', 'Kingsly', 'Lion', 9, 'M', 3, '161','117'),
('40', 'Eric', 'Lion', 11, 'M', 3, '121','113'),
('41', 'tukyufyu', 'Lion', 2, 'M', 3, '121','173'),
('61', 'hgndghmd', 'Elephant', 6, 'F', 225, '201','111'),
('62', 'sghgdht', 'Elephant', 10, 'F', 230, '201','111'),
('63', 'xgnyn', 'Elephant', 5, 'F', 300, '111','121'),
('64', 'sbfdfbng', 'Elephant', 11, 'F', 173, '111','121'),
('65', 'fdghd', 'Elephant', 12, 'F', 231, '111','666'),
('66', 'Fred', 'Elephant', 17, 'F', 333, '151','147'),
('67', 'Mary', 'Elephant', 3, 'F', 272, '81','148'),
('68', 'Jane', 'Elephant', 8, 'F', 47, '71','136'),
('69', 'dfgjtjt', 'Elephant', 9, 'F', 131, '161','172'),
('70', 'Eric', 'Elephant', 10, 'F', 333, '121','136'),
('71', 'tukyufyu', 'Elephant', 7, 'M', 114, '121','731');
INSERT INTO Keeper VALUES
('1', 'Roger', 'tdfhuihiu'),
('2', 'Sidra', 'rgegegtnrty'),
('3', 'Amit', 'ergetetnt'),
('4', 'Lucia', 'dvojivhwivih');
INSERT INTO Care_Role VALUES
('32', '1', 'feeding'),
('32', '2', 'washing'),
('61', '1', 'feeding'),
('62', '1', 'feeding'),
('63', '1', 'feeding'),
('64', '1', 'feeding'),
('65', '1', 'feeding'),
('66', '1', 'feeding'),
('67', '1', 'feeding'),
('68', '1', 'feeding'),
('69', '1', 'feeding'),
('70', '1', 'feeding'),
('71', '1', 'feeding'),
('11', '4', 'feeding'),
('12', '4', 'feeding'),
('13', '4', 'feeding'),
('14', '4', 'feeding'),
('15', '4', 'feeding'),
('16', '4', 'feeding'),
('17', '4', 'feeding'),
('18', '4', 'feeding'),
('19', '4', 'feeding'),
('20', '4', 'feeding'),
('21', '4', 'feeding');
So far what I've managed to come up with is this:
SELECT Keeper.Keeper_Name, Animal.Species, COUNT(Animal.Species)
FROM Keeper
JOIN Care_Role
ON Keeper.Staff_ID = Care_Role.Staff_ID
JOIN Animal
ON Care_Role.ID = Animal.ID
GROUP BY Animal.Species
But this is returning more than just the name (which is what I want), as well as showing all the people who have looked after animals, rather than just those who have looked after 10 or more, I was wondering if anyone had any ideas on how to help with this? Many thanks!

Answer 1

Your query should be returning an error, because Keeper.Keeper_name is not in the GROUP BY. You have made a good attempt. A reasonable way to start the query is:
SELECT k.Keeper_Name, a.Species, COUNT(*)
FROM Keeper k JOIN
Care_Role cr
ON k.Staff_ID = cr.Staff_ID JOIN
Animal a
ON cr.ID = a.ID
GROUP BY k.Keeper_Name, a.Species;
This will return the number of animals of a given species that each keeper cares for.
Note the following:
Table aliases are abbreviations for the table.
All column names are qualified.
This uses the shorthand of COUNT(*) instead of counting some particular column.
Your question adds an additional condition about 10 animals. You can fit that in using a HAVING clause.