[CONSTRAINT [symbol]] FOREIGN KEY
[index_name] (index_col_name, ...)
REFERENCES tbl_name (index_col_name,...)
[ON DELETE reference_option]
[ON UPDATE reference_option]
reference_option: RESTRICT | CASCADE | SET NULL | NO ACTION | SET DEFAULT
https://docs.oracle.com/cd/E17952_01/mysql-5.6-en/create-table-foreign-keys.html
A foreign key can be defined in either a CREATE TABLE statement or an ALTER TABLE statement.
Using a CREATE TABLE statement
Syntax
The syntax for creating a foreign key using a CREATE TABLE statement is:
CREATE TABLE table_name
(
column1 datatype null/not null,
column2 datatype null/not null,
...
CONSTRAINT fk_column
FOREIGN KEY (column1, column2, ... column_n)
REFERENCES parent_table (column1, column2, ... column_n)
);
References: https://www.techonthenet.com/oracle/foreign_keys/foreign_keys.php