title: MySQL - Error Code 1215, cannot add foreign key constraint
body: <p>i got these two succesfull queries:</p>
  
  <pre><code>create table Donors (
      donor_id int not null auto_increment primary key,
      gender varchar(1) not null,
      date_of_birth date not null,
      first_name varchar(20) not null,
      middle_name varchar(20),
      last_name varchar(30) not null,
      home_phone tinyint(10),
      work_phone tinyint(10),
      cell_mobile_phone tinyint(10),
      medical_condition text,
      other_details text );
  </code></pre>
  
  <p>and</p>
  
  <pre><code>create table Donors_Medical_Condition (
      donor_id int not null,
      condition_code int not null,
      seriousness text,
      primary key(donor_id, condition_code),
      foreign key(donor_id) references Donors(donor_id)    );
  </code></pre>
  
  <p>but when i try this one:</p>
  
  <pre><code>create table Medical_Conditions (
      condition_code int not null,
      condition_name varchar(50) not null,
      condition_description text,
      other_details text,
      primary key(condition_code),
      foreign key(condition_code) references Donors_Medical_Condition(condition_code) );
  </code></pre>
  
  <p>i get "Error Code: 1215, cannot add foreign key constraint"</p>
  
  <p>i dont know what am i doing wrong.</p>