Normalization
process of converting complex data structures into simple, stable data structures
View integration
combine normalized data requirements from all user interfaces into one consolidated logical database model
Primary Key
an attribute (or combination of attributes) whose value is unique across all occurrences of a relation
Relational database model
data represented as a set of relatable tables or relations
Relation
named 2 dimension table of data. consist of a set of named columns and an arbitrary number of unnamed rows
Well-structured relations (table)
relation that contains a min amount of redundancy and allows users to insert, modify, and delete rows w/o error/instances
Functional Dependency
constraint b/w 2 attributes in which the value of one attribute is determined by the value of another attribute
Second Normal Form (2nf)
if every non-primary key attribute is functionally dependent on the whole primary key
Third Normal Form
relation that is in 2NF and has no functional dependencies between 2 or more non-primary key attributes
Foreign Key
attribute that appears as a non primary key attribute in one relation and as a primary key attribute in another relation
Referential Integrity
rule that states that either each foreign key value must match a primary key value in another relation or be null
recursive foreign key
foreign key in a relation that references the primary key values of that same relation
Synonym
2 different names that are used for the same attribute (emp_id and Emp_No)
Homonym
single attribute that is used for 2 or more different attributes (ex account>loan, bank, savings)
Field
smallest unit of named application data recognized by system software
Data type
coding scheme recognized by system software for representing organizational data
Calculated field
field that can be derived from other database fields.
Default Value
value a field will assume unless an explicit value is entered for that field
Null Value
a special value, distinct from 0, blank, or any other value, that indicates that the value for the field is missing/unknown
physical table
a named set of rows and columns that specifies the fields in each row of the table
Denormalization
process of splitting/combining normalized relations into physical table based on affinity of use of rows and fields
Physical file
named set of table rows stored in a contiguous section of secondary memory
File organization
technique for physically arranging the records of a file
Pointer
field of data that can be used to locate a related field or row of data
Sequential File organization
rows in a file are stored sequence according to a primary key value
Indexed file organization
A file organization in which rows are stored either sequentially or nonsequentially, and an index is created that allows software to locate individual rows.
Index
A table used to determine the location of rows in a file that satisfy some condition.
Secondary key
One or a combination of fields for which more than one row may have the same combination of values.
Hashed file organization
file organization in which the address of each row is determined using an algorithm