Term
|
Definition
Insert Anomaly:When you insert a record without having it stored on the related record.
Delete Anomaly:When you delete some information and lose valuable related information at the same time.
Modification Anomaly: Any change made to your data will require you to scan all records to make the changes multiple time. |
|
|
Term
| A well structured relation is |
|
Definition
a relation that contains MINIMAL REDUNDANCY and allows users to INSERT, MODIFY, and DELETE rows in a table WITHOUT ERRORS or INCONSISTENCIES
If a relation is not well structured, anomalies may occur |
|
|
Term
|
Definition
| A composite key is when more than one field makes up a primary or foreign key. |
|
|
Term
|
Definition
| any attribute that you can use to determine the value assigned to other attribute(s) in the same row |
|
|
Term
|
Definition
| When no primary key attribute (or components of a primary key attribute) can be null |
|
|
Term
|
Definition
| No multivalued attributes, and every attribute value is atomic (cannot be decomposed). All relations are in 1st normal form |
|
|
Term
|
Definition
| Identifiers that enable a dependent relation ( on the many side of a relationship) to refer to its parent relation (on the one side of the relationship) |
|
|
Term
|
Definition
A constraint between two attributes in which the value of one attribute is determined by the value of another attribute.
Birthday is functionally dependent on SSN
If you know the SSN, you know the DOB |
|
|
Term
|
Definition
| Attributes with same name but different meanings |
|
|
Term
|
Definition
| The process of decomposing relations with anomalies to produce smaller, well-structured relations |
|
|
Term
|
Definition
| A value, distinct from zero, that represents the absence of any value in a field |
|
|
Term
| Partial Functional Dependency |
|
Definition
| A functional dependency which one or more nonkey attributes are functionally dependent on part (but not all) of the primary keys |
|
|
Term
|
Definition
| Unique identifiers of the relation in order to guarantee that all rows are unique. |
|
|
Term
| Referential Integrity Constraint |
|
Definition
| rule states that any foreign key value (on the relation of the many side) MUST match a primary key value in the relation of the one side. |
|
|
Term
|
Definition
| Unique rows and no multivalued attributes (all relations are in first normal form) |
|
|
Term
| Components of the Relational Model (3) |
|
Definition
Data Structure: Tables, Rows and Columns
Data Manipulation: Powerful SQL operations for retrieving and modifying data
Data integrity: Mechanisms for implementing business rules that maintain integrity of manipulated data |
|
|
Term
|
Definition
| 1 NF + every non-key attribute is fully functionally dependent on the ENTIRE primary key (no partial dependencies) |
|
|
Term
|
Definition
| Combining multiple primary keys into a single primary key in order to simplify a table. |
|
|
Term
|
Definition
| Two or more attributes with different names but same meanings |
|
|
Term
|
Definition
| 2NF + No transitive dependencies |
|
|
Term
|
Definition
| When an attribute is functionally dependent on another attribute that is not the primary key |
|
|
