Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Data.Mgmt.Systems1
Chapter5(LogicalDatabaseDesignAndTheRelationalModel)
| Question | Answer |
|---|---|
| The relational data model consists of the following three components: | (1) Data Structure (2) Data manipulation (3) Data integrity |
| A _____ is a named, two-dimensional table of data. | relation |
| A _____ is an attribute (or combination of attributes) that uniquely identifies each row in a relation. | primary key |
| A _____ is designated by underlining the attribute name. | primary key |
| A _____ is a primary key that consists of more than one attribute. | composite key |
| A _____ is an attribute (possibly composite) in a relation of a database that serves as the primary key of another relation in the same database. | foreign key |
| There are three reasons that you should create an instance of your relational schema with sample data. | (1) The sample data provide a convenient way to check the accuracy of your design. (2) The sample data help improve communications with users in discussing your design. (3) You can use the sample data to develop prototype applications and to test querie |
| The purpose of the several types of constraints (business rules) in the relational data model is to... | ...facilitate maintaining the accuracy and integrity of data in the database. |
| The major types of integrity constraints are: | Domain constraints, entity integrity, referential integrity, and action assertions. |
| A _____ is the set of values that may be assigned to an attribute. | domain |
| A _____ usually consists of the following components: domain name, meaning, data type size, and allowable values or allowable range. | domain definition |
| The _____ rule is designed to ensure that every relation has a primary key, and that the data values for that primary key are all valid. | entity integrity |
| The _____ rule states the following: No primary key attribute (or component of a primary key attribute) may be null. | entity integrity |
| A _____ is a rule that maintains consistency among the rows of two relations. | referential integrity constraint |
| The _____ rule states that if there is a foreign key in one relation, either each foreign key value must match a primary key value in another relation, or the foreign key value must be null. | referential integrity constraint |
| To create table definitions for tables, the _____ statements from the SQL data definition language are used. | CREATE TABLE |
| A _____ contains minimal redundancy and allows users to insert, modify, and delete the rows in a table without errors or inconsistencies. | well-structured relation |
| A(n) _____ in an error or inconsistency that may result when a user attempt to update a table that contains redundant data. | anomaly |
| The three types of anomalies are: | (1) Insertion anomaly (2) Deletion anomaly (3) Modification anomaly |
| The three reasons in the process of transforming E-R diagrams to relations are: | (1) CASE tools often cannot model more complex data relationships (2) There are sometimes legitimate alternatives where you will need to choose a particular solution. (3) Be prepared to perform a quality check on the results obtained with a CASE tool. |
| Step 1 in transforming E-R diagrams to relations is... | Map Regular Entities |
| Step 2 in transforming E-R diagrams to relations is... | Map Weak Entities |
| Step 3 in transforming E-R diagrams to relations is... | Map Binary Relationships |
| Step 4 in transforming E-R diagrams to relations is... | Map Associative Entities |
| Step 5 in transforming E-R diagrams to relations is... | Map Unary Relationships |
| Step 6 in transforming E-R diagrams to relations is... | Map Ternary (and n-ary) Relationships |
| Step 7 in transforming E-R diagrams to relations is... | Map Supertype/Subtype Relationships |
| A nonkey attribute is also called a _____. | descriptor |
| A _____ is a serial number or other system assigned primary key for a relation. | surrogate primary key |
| A surrogate key should be created when any of the following conditions hold: | (1) There is a composite primary key (2) The natural primary key is inefficient (3) The natural primary key is recycled |
| A _____ is a foreign key in a relation that references the primary key values of that same relation. | recursive foreign key |
| _____ is a formal process for deciding which attributes should be grouped together in a relation so that all anomalies are removed. | Normalization |
| There are three major occasions during the overall database development process when you can usually benefit from using normalization... | (1) During conceptual data modeling (2) During logical database design (3) Reverse-engineering older systems |
| Four main goals of normalization are: | (1) Minimize data redundancy (2) Simplify the enforcement of referential integrity constraints (3) Make it easier to maintain data (4) Provide a better design that is an improved representation of the real world and a stronger basis for future growth |
| A _____ is a state of a relation that results from applying simple rules regarding functional dependencies to that relation. | normal form |
| There are six kinds of normal form: | (1) First normal form (2) Second normal form (3) Third normal form (4) Boyce-Codd normal form (5) Fourth normal form (6) Fifth normal form |
| First normal form is... | ...any multivalued attributes have been removed, so there is a single value at the intersection of each row and column of the table. |
| Second normal form is... | ...any partial functional dependencies have been removed. |
| Third normal form is... | ...any transitive dependencies have been removed. |
| Boyce-Codd normal form is... | ...any remaining anomalies that result from functional dependencies have been removed. |
| Fourth normal form is... | ...any multivalued dependencies have been removed. |
| Fifth normal form is... | ...any remaining anomalies have been removed. |
| A _____ is a constraint between two attributes or two sets of attributes. | functional dependency |
| The attribute on the left side of the arrow in a functional dependency is called a _____. | determinant |
| A _____ is an attribute, or combination of attributes, that uniquely identifies a row in a relation. | candidate key |
| A candidate key must satisfy two properties: | (1) Unique identification (2) Nonredundancy |
| A relation is in _____ if the following two constraints both apply: (1)there are no repeating groups in the relation & (2)a primary key has been defined, which uniquely identifies each row in the relation. | first normal form (1NF) |
| Manipulating the data in the table can lead to anomalies such as the following: | (1) Insertion anomaly (2) Deletion anomaly (3) Update anomaly |
| A relation is in _____ if it is in first normal form and contains no partial dependencies. | second normal form (2NF) |
| A _____ exists when a nonkey attribute is functionally dependent on part (but not all) of the primary key. | partial functional dependency |
| A relation is in _____ if it is in second normal form and no transitive dependencies exist. | third normal form (3NF) |
| A _____ in a relation is a functional dependency between two (or more) nonkey attributes. | transitive dependency |
| _____ are two (or more) attributes having different names but the same meaning, as when they describe the same characteristic of an entity. | synonyms |
| A(n) _____ is an alternative name used for an attribute. | alias |
| An attribute that may have more than one meaning is called a _____. | homonym |
| A(n) _____ is a primary key whose value is unique across all relations. | enterprise key |
Created by:
58800073