title: "BLOB/TEXT column used in key specification without a key length" error in Django
body: <p>I have this model in my Django project: </p>
  
  <pre><code>class Institution(models.Model):
      name = models.CharField(unique=True, max_length=100, blank=True)
      description = models.TextField(max_length=500, null=True, blank=True)        
      def __str__(self):
          return self.name
  </code></pre>
  
  <p>I run my project completely when I use <code>SQLite</code> ,but when I change my database engine to <code>Mysql</code> I got this error: </p>
  
  <pre><code>MySQLdb._exceptions.OperationalError: (1170, "BLOB/TEXT column 'name' used in key specification without a key length")
  </code></pre>
  
  <p><strong><em>What I must to do?</em></strong> </p>