MySQL error cannot add foreign key constraint

Question

what is wrong?

mysql> create table price(
    -> p_code char(1) not null,
    -> p_description varchar(20),
    -> p_rentfee decimal(2,2) not nul         


        

Answer 1

• Engine should be the same e.g. InnoDB
• Datatype should be the same, and with same length. e.g. VARCHAR(20)
• Collation Columns charset should be the same. e.g. utf8
  Watchout: Even if your tables have same Collation, columns still could have different one.
• Unique - Foreign key should refer to field that is unique (usually primary key) in the referenced table.