MySQL foreign key creation failure Solution

Create persons:
Create table 'persons '(
'Id _ P' int (11) not null AUTO_INCREMENT,
'Lastname' varchar (10) default null,
'Firstname' varchar (10) default null,
'Address' varchar (50) default null,
'City' varchar (10) default null,
Primary key ('Id _ p ')
);

Create another table orders:
Create table 'Orders '(
'Id _ o' int (11) not null AUTO_INCREMENT,
'Orderno' int (11) not null,
'Id _ P' int (11) not null,
Primary key ('Id _ o '),
Foreign key ('Id _ p') REFERENCES 'persons '('Id _ p ')
);

You can use the show create table orders statement to query orders Information and find that the foreign key is not created successfully. I checked some information and finally found the reason. Mysql creates a table of the MyISAM type by default. You must specify the table type as innodb:

Create table 'Orders '(
'Id _ o' int (11) not null AUTO_INCREMENT,
'Orderno' int (11) not null,
'Id _ P' int (11) not null,
Primary key ('Id _ o '),
Foreign key ('Id _ p') REFERENCES 'persons '('Id _ p ')
) ENGINE = InnoDB;

However, the following error message is displayed:
ERROR 1005 (HY000): Can't create table 'test. orders '(errno: 150)
Set the persons Table type to innodb.

To sum up the following situations:
1. Foreign keys and referenced Foreign keys are of different types, such as integer and double
2. The column to be referenced cannot be found.
3. The character encoding of the table is different.
4. inconsistent data engine types, such as innodb and myisam