MySQL 8.0

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

CREATE Table orderingNulls (num1 INT NULL, num2 INT NOT NULL);

INSERT INTO orderingNulls (num1, num2) VALUES (1,1), (NULL,1), (1,2), (2,1),(2,2),(NULL,2)

Records: 6  Duplicates: 0  Warnings: 0

SELECT * FROM orderingNulls;

num1
num2

1
1

null
1

1
2

2
1

2
2

null
2

#NULLs first but in descending order
SELECT * FROM orderingNulls ORDER BY !ISNULL(num1), num1 desc, num2;
#NULLS last but in ASC order
SELECT * FROM orderingNulls ORDER BY ISNULL(num1), num1, num2;

num1
num2

null
1

null
2

2
1

2
2

1
1

1
2

num1
num2

1
1

1
2

2
1

2
2

null
1

null
2

num1	num2
1	1
null	1
1	2
2	1
2	2
null	2

num1	num2
null	1
null	2
2	1
2	2
1	1
1	2

num1	num2
1	1
1	2
2	1
2	2
null	1
null	2