MySQL 8.4 Reference Manual Including MySQL NDB Cluster 8.4
RETURN expr
        The RETURN statement terminates
        execution of a stored function and returns the value
        expr to the function caller. There
        must be at least one RETURN
        statement in a stored function. There may be more than one if
        the function has multiple exit points.
      
        This statement is not used in stored procedures, triggers, or
        events. The LEAVE statement can
        be used to exit a stored program of those types.