title: MySQL change collation error
body: <p>I try to change collation on MySQL table from <code>latin1_swedish_ci</code> to <code>utf8_general_ci</code>. I used query like this:</p>
  
  <pre><code>ALTER TABLE mytable
  MODIFY myfield varchar(10) CHARACTER SET utf8 COLLATE utf8_general_ci;`
  </code></pre>
  
  <p>But this query result <code>errno 150</code>. I think this is because foreign key that reference into mytable. I try to delete all record on my database, I drop all foreign keys also. I try to run again. But still result <code>errno 150</code>.</p>
  
  <p>Any idea about my problem ?</p>