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59 Cards in this Set
- Front
- Back
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What is an attribute?
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a property of an entity
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What is an entity?
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a thing or object that's distinguishable from other entities
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What is an entity type?
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Description of the attributes an entity set has in common (in other words, a class description)
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In diamond notation, how do you represent an entity type?
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square box
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in diamond notation, how do you represent an attribute?
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a circle
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in diamond notation, how do you specify something is a key attribute?
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underline label of attribute
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What is a composite attribute?
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an attribute that is composed of other attributes
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in diamond notation, how do you represent composite attributes?
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attributes connected to the composite attributes
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What is a multi-valued attribute?
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an attribute that can have > 1 value
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how do you represent a multi-value attribute?
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two circles around an attribute
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What is a derived attribute?
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an attribute who's value can be derived from other attribute values
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how do you represent a derived attribute in diamond notation?
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dotted circle around the attribute
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What is the purpose of Crow's Feet notation?
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reduce screen clutter
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How does crow's feet represent entities and attributes?
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a uml box, entityTypeName as title, as list of attributes below, key underlined
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What is a relationship?
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an association between one or more entities
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how do you represent a relationship in diamond notation?
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a diamond
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What is participation?
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Example: does a customer HAVE to rent a movie to be a part of the relationship? (some entities may or may not)
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in diamond notation, what does (x, y) mean?
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min max notation
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in diamond notation, what does double lines mean?
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total participation
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in crow's feet, how do you represent cardinality?
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1=one, crow's foot = many
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in crow's feet, how do you representation?
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0 (or circle) = partial participation
1 = total participation |
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what's another to think of crow's feet?
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min max, participation = min
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When you create a relation using crow's feet, and try to connect them to two entity types, what side would you like on to see A's participation and cardinality information?
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the relation's connection to B
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What does it mean to borrow a key?
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when you create a relation, the DBMS Designer automatically creates a foreign key for you when it is needed?
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What can you specify with the DBMS in relation to key borrowing?
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Whether or not the borrowed key becomes a part of the key
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What is a weak entity type?
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a type that doesn't have sufficient attributes to have a key from within its own attributes
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how do you represent a weak entity type in diamond notation?
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two squares around an entity type
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how do you represent a partial key in diamond notation
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dotted underline instead of solid
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Can owning relationships cascade?
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Yes
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how do you represent an owning relationship type in diamond notation?
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double diamond
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What types of modeling does crow's feet and diamond notation represent?
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Entity Relationship Modeling (ER)
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What type of modeling is used in MySQL Workbench?
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Extended Entity Relationship Modeling (EER)
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What are the extensions EER adds to ER Modeling?
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-Superclass / Subclass relationships
-specialization -categories |
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how do you represent a superclass / subclass relationship in EER modeling?
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you draw a line that connects the super class with its subclasses, and specify the specialization
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What are the different types of specialization subclasses can have?
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special attributes
specialized relationship types |
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What are the two types of Specialization?
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overlapping and disjoint
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What is overlapping specialization?
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an entity can be all subclasses
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What is disjoint specialization?
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an entity must be only one subclass
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how do you represent overlapping specialization?
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a circle with an "o" in it
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How do you represent disjoint specialization?
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a circle with a "d" in it
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What is a category?
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a subclass that doesn't have a general superclass
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What is an example of a category?
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a performer who can be a group or individual
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What is the general rule in EER modeling?
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keep the diagram simple until it needs to be more complicated
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What are the three EER Modeling design strategies?
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-top down
-bottom up -inside out |
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What is the top down approach?
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start with high level and add detail
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What is the bottom up approach?
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start with details, and add generalizations to it
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What is the inside-out approach?
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start with what you know, and figure out what you don't know
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What is the first step in integrating multiple ER diagrams together?
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find what the diagrams have in common and start there
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What is the first step in mapping an EER Diagram to a relational schema?
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map entity types
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What is the second step in mapping an EER Diagram to a relational schema?
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weak entity types
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What is the third step in mapping an EER Diagram to a relational schema?
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binary 1 - 1 relationship types
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What is the fourth step in mapping an EER Diagram to a relational schema?
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binary 1 - m relationship types
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What is the fifth step in mapping an EER Diagram to a relational schema?
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binary n - m relationship types
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What is the sixth step in mapping an EER Diagram to a relational schema?
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n-ary relationship types
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What is the seventh step in mapping an EER Diagram to a relational schema?
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multivalued attributes
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What is the eighth step in mapping an EER Diagram to a relational schema?
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inheritance hierarchies
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What the algorithm for step one?
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create a table for each regular entity type. For each table:
- 1 column for each simple attribute - you choose whether or not to represent derived attributes -key of entity type denotes table's key |
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If you choose to represent derived attributes in step one, when is the attribute calculated?
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when the table is populated with data
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What is the algorithm for step two?
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create a table for each weak entity type. For each table:
-one column for simple attributes -Include columns for the primary key of owning entity types and indicate they are foreign keys -the primary key is the partial key plus the borrowed keys |
