For CMPS 342, Database systems, the most useful topics are

 

1.       Set (of records) related operators: Cartesian Product, Division,
selection

2.       The First-order Logics.

 

A simple Hotel database, an set of queries can be found in the following link:

 

http://www.cs.csubak.edu/~hwang/CS342/QueriesOnHotel.txt

 

Those queries (not involving aggregate functions) can be answered in set
operator

And first order logical.