By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.
create table customer (id int auto_increment primary key,
grade int, city varchar(12))
insert into customer (grade, city) values
(4, 'Columbo'),
(8, 'Los Angeles')
SELECT *
FROM customer
WHERE grade >
(SELECT MAX(grade)
FROM customer
WHERE city='New York');
SELECT *
FROM customer
WHERE grade >
(SELECT COALESCE(MAX(grade), -1)
FROM customer
WHERE city='New York');
| id | grade | city |
|---|---|---|
| 1 | 4 | Columbo |
| 2 | 8 | Los Angeles |
insert into customer (grade, city) values
(5, 'New York')
SELECT *
FROM customer
WHERE grade >
(SELECT COALESCE(MAX(grade), -1)
FROM customer
WHERE city='New York');
| id | grade | city |
|---|---|---|
| 2 | 8 | Los Angeles |