2141-W2013 Mid-term Prep

Next week Monday, Feb 18 – Midterm Covers everything before normalization Wednesday, Feb 20 – Ass 3 (normalization) due – Wrap up normalization Friday, Feb 22 – Quiz 3 (normalization) – Set the stage for after spring break

Core database concepts Database records Attributes and their domains Rows must be unique Keys: super, candidate, primary foreign What are the anomalies trying to avoid: – Deletion/insertion/update

Conceptual Database Design How to take a description of a real-world rules and create an ER diagram – Specify cardinality/ordinality of a relationship – The differences between entities, attributes, and relationships (and when you might want to promote an attribute to an entity or a relationship to an associative entity) – How to indicate the primary key

Logical Database design How to convert an ER diagram to the appropriate set of tables – What are the rules for creating tables For entities For relationships of different cardinalities (1-1, 1-many, many-to-many) For relationships of different modalities (unary, binary, ternary, etc.)

Relational Algebra Core operations – Select – Project – Rename – Union – Intersection – Set difference – Division – Cartesian product – Natural join – Conditional join (theta) The format of the operation Union compatibility The schema of the relationship returned The data in the relationship returned How to parse a query How to form a query High level notion of efficiency

Midterm format ~ 5 short and snappy – Multiple choice – Compare/contrast/T or F and explain ER diagram ER diagram to tables Relational algebra – As in quiz: Do you know the basic mechanics Can you parse what a query does Can you create a query to achieve a goal Approximate weights 20% basic concepts 20% ER diagram 20% ER diagram to tables 40% Relational algebra Chinese menu?

Strategies Go for partial points – Show your work – Use comments Explain what you are trying to achieve Provide your interpretation State any assumptions – Be neat – highlight (put a box around it) your final result if you have a lot of attempts – Use parentheses to help show your logic – Use partial steps and assign them to relations if it helps you think about it (R1 = ___), but make sure that it is clear what you are doing and how the pieces then fit together Be succinct

Relational Algebra Do you know all the relations needed Do you know the output needed (final projection/selection) Do you know how to combine the parts