title: ERROR 1052 (23000): Column 'course_id' in where clause is ambiguous
body: <p>I'm new to MySQL so please tell me if my question is missing information,</p>
  
  <p>I have a query that works fine:</p>
  
  <pre><code>select au.email, sm.created, sm.grade, sm.max_grade
  from auth_user au, courseware_studentmodule sm
  where sm.student_id = au.id
  and course_id = 'MyCourse'
  and sm.module_type = 'problem';
  </code></pre>
  
  <p>But when I want to add another column from a different table:</p>
  
  <pre><code>select au.email, sm.created, sce.created , sm.grade, sm.max_grade
  from auth_user au, courseware_studentmodule sm,  student_courseenrollment sce
  where sm.student_id = au.id and sm.student_id = sce.id
  and course_id = 'MyCourse'
  and sm.module_type = 'problem';
  </code></pre>
  
  <p>I get this error </p>
  
  <pre><code>ERROR 1052 (23000): Column 'course_id' in where clause is ambiguous
  </code></pre>
  
  <p>Anyone know why?</p>
  
  <p>Thanks</p>