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2141-W2013 Mid-term Prep

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

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2141-W2013 Mid-term Prep

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  1. 2141-W2013Mid-term Prep

  2. 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

  3. 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

  4. 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

  5. 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.)

  6. 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

  7. 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?

  8. 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

  9. 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

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