title: Master-Detail relationship in design tables in mysql
body: <p>I need to create 2 tables rosters and records, whereby each roster has many records. 
  A roster is based on class and there is maximum 1 roster for each class per day.
  A record can have many students. </p>
  
  <p>I wonder that this <strong>master-detail</strong> relationship design is effective?
  My friend suggests that everything could be done in record table, since we want to display a roster of all the students in a class in a specific day. So in the master-detail approach, it takes query on <strong>2 tables</strong> to accomplish the task, in contrast, it take only <strong>1 query</strong> if there is only one record table.<br>
  Please advise. </p>