title: MySQL case sensitive foreign key for textual data
body: <p>I have <code>ISO 639-2</code> language codes (eng, fre, hin, etc.) in english as primary key in my master table. This column is foreign key in may other tables. Now my issue is even though my master have only lower case values, due to human error some values were added in other tables with language id in mixed cases. Even though there was foreign key, it didn't prevent it from happening.<br>
  Now this is first time I am working in MySQL, previously I worked on Oracle and it applies case sensitivity to keys. What should be done to have same functionality in MySQL?
  Also what should be the column type?<br>
  Right now it is <code>varchar(3)</code>. Should I convert it to something else? I am not going to use any <code>like</code> condition in any of the query, only <code>=</code> and <code>in</code>.</p>