- Schema Design: A database describes data. The data is
organized into connected tables. Schema Design is about how to
design these structures.
- Relational Algebra: You cannot understand databases without
understanding relational algebra. It explains what SQL does. It
forms the internal representation of a query. This internal
representation is the starting point for query optimization, and
query execution.
- Transaction Management: If multiple users are viewing and
updating the same data at the same time, how should these actions be
coordinated? Without some control, the database will quickly become
broken. E.g. the same airplane seat could be sold twice.