CREATE TABLE emps (id INT(10) AUTO_INCREMENT,
fname VARCHAR(50) NOT NULL,
sname VARCHAR(50) NOT NULL);
INSERT INTO emps (fname) VALUES ('John');
In a proper RDBMS, that would fail for violating a constraint. MySQL/MariaDB just massage the missing sname into an empty string, which is about as valid as just sticking 'sldfjpsdj;ksdj;fsdljkfsd.'
"There is no distinctly American criminal class except Congress." -- Mark Twain