Some people in the vet's owners table have no pet on file yet. Pick their name: the owners whose id isn't among the owner_ids in pets. Careful: some owner_ids are empty.
The tables
owners
id
name
city
phone
1
Lena
Oslo
555-0101
2
Marco
Rome
NULL
3
Priya
Oslo
555-0103
4
Omar
Cairo
NULL
5
Sofia
Rome
555-0105
5 rows
pets
id
name
kind
age
weight
owner_id
1
Biscuit
dog
3
12
1
2
Mochi
cat
5
4
1
3
Pepper
dog
8
20
2
4
Nemo
fish
1
NULL
3
5
Luna
cat
2
3
3
6
Rex
dog
11
30
NULL
7
Kiwi
bird
4
NULL
5
8
Tofu
cat
7
5
NULL
8 rows
owners
id
name
city
phone
1
Lena
Oslo
555-0101
2
Marco
Rome
NULL
3
Priya
Oslo
555-0103
4
Omar
Cairo
NULL
5
Sofia
Rome
555-0105
5 rows
pets
id
name
kind
age
weight
owner_id
1
Biscuit
dog
3
12
1
2
Mochi
cat
5
4
1
3
Pepper
dog
8
20
2
4
Nemo
fish
1
NULL
3
5
Luna
cat
2
3
3
6
Rex
dog
11
30
NULL
7
Kiwi
bird
4
NULL
5
8
Tofu
cat
7
5
NULL
8 rows
query.sql
SELECT name
FROM owners
WHERE id NOT IN (
-- your code here: the owner_id from pets, with WHERE dropping the empty ones
);
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Result
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