Syntax:
<=>

NULL-safe equal. This operator performs an equality comparison like the
= operator, but returns 1 rather than NULL if both operands are NULL,
and 0 rather than NULL if one operand is NULL.

The <=> operator is equivalent to the standard SQL IS NOT DISTINCT FROM
operator.

URL: https://dev.mysql.com/doc/refman/8.0/en/comparison-operators.html

