Noticed that the ClassCode values have a slash in the same position which may indicate that the column can be decomposed, such as the values before the slash indicate the department and after the slash, a unique value within the department. If so, then there should be two columns. Another ways of determining if this is a compound column is to search for a query that has "where ClassCode like '123456/%' ". Also look for another table that has a candidate key that matches the values before the slash.

Insert xClass values ('123456/12','Research')

Insert xClass values ('678910/13','Technology')

Insert xClass values ('123456/13','Crime')

Insert xClass values ('123456/14','Business')

Insert xClass values ('123456/15','Accounting')