Structural dependence - ANSWER A change in any file's structure requires the
modification of all programs using that file.
Data dependence - ANSWER A change in any files data characteristics requires
changes of all data access programs
Data redundancy - ANSWER Same information stored in more than one place
Problems due to uncontrolled data redundancy - ANSWER Data inconsistency ( lack of
data integrity)
Modification Anomalies - ANSWER Inconsistent data due to modifications
Insertion anomaly - ANSWER Data inconsistency due to insertion
Deletion anomaly - ANSWER Data inconsistency due to deletion of data
Entities - ANSWER Entity is anything like person, place, event or things for which data is
collected
Attributes - ANSWER Defines characteristics of an entity
Entity set - ANSWER Set of entities of similar type
, Table - ANSWER Stores group of related entities
Key - ANSWER Consists of one or more attributes that determine other attributes in an
entity
Composite key - ANSWER Key that is composed of more than one attribute
Super key - ANSWER Attribute or comibination of attributes that uniquely identify each
row in a table
Candidate key - ANSWER Minimal super key, doesn't contain subset of attributes that is
itself a super key
Primary key - ANSWER Candidate key selected to identify an entity
Can't have null values
Enforce entity integrity
Super key as well as candidate key
Secondary key - ANSWER Used for retrieval purpose
Single attribute or set of attributes
Maintains indexing on secondary keys
Values duplicated
Foreign key - ANSWER Attribute or set of attributes in one table whose values is either
match primary key values or be null
Logically link one table with another
Referential integrity can be implemented
Data dictionary - ANSWER Is a repository of information about the data in the database.
Metadata
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