title: How to add to a table cell without overriding the data?
body: <p>I am building a GUI grading system in C# that implements SQL Server 2012. When the program begins there are tabs that control different aspects of the program such as adding, updating, or deleting records; viewing a grade GridView for all or single student; and then viewing all student records. Right now I have all of a student's grades in 1 cell in a table called StudentGrades, it looks like this:</p>
  
  <pre><code>Student ID     Student Grades
  00001          100, 58, 72, 10, 25, 50, 93, 74, 30
  00002          10, 40
  00003          88, 60, 20, 45
  </code></pre>
  
  <p>As you can see not every student has the same amount of grades, so I thought it would be easier to have all the grades occupy 1 cell rather than have a table with empty cells.</p>
  
  <p>What I am trying to accomplish is when the user updates a student record and adds a new grade, I want the program to query the database and SELECT the StudentGrades from the StudentGrades table and then return the value. Once it is returned, I want to add the new grade to the result and then update the database with a new script. Kind of like this:</p>
  
  <pre><code>string select = "select StudentGrades from StudentGrades where Student_ID = inputStudentID";
  SqlCommand command = new SqlCommand(select, conn);
  SqlDataReader reader = command.ExecuteReader();
  string temp = reader;
  temp += "," + newStudentGrade;
  //Script to update table here
  </code></pre>
  
  <p>Is this possible in Sql Server 2012 and C#? What value would reader hold after querying the table? </p>