The MATCH clause in the SQL standard controls how NULL values in a composite (multiple-column) foreign key are handled when comparing to a primary key. MySQL essentially implements the semantics defined by MATCH SIMPLE.
Which keyword is used to specify the foreign key after the table is created?
In MySQL foreign key definition syntax, there are various components, namely, FOREIGN KEY, CONSTRAINT, REFERENCES and ON DELETE. The REFERENCES clause names the parent table and the index columns in the table.