Quiz 1 - Part 3 Flashcards
A table is perceived as a t….-d……. structure composed of r…. and c…..
two-dimensional / rows and columns
each table row (tuple) represents a single e…. o…… within the e…. s….
entity occurrence / entity set
Each table column rerpresent an a….., and each column has a distinct name
attribute
Each intersection of a r…. and a c……. represent a single d…. v…..
row and column / data value
All values in a column must conform to the same d…. f….
data format
Each column has a specific range of values known as the a…… d…….
attribute domain
the order of the rows and columns is i…… to the DBMS
IMMATERIAL
Each table must have an a….. or combination of a….. that u….. identifies each row
attribute / attributes / uniquely
Consist of one or more attributes that determines other attribute
Keys
Keys are used to ensure that each row in a table is u….. identifiable
uniquely
Keys are used to establish r….. among tables and to ensure i…. of the data
relationships / integrity
Attribute or combination of attributes that uniquely identifies any give row
Primary key
Value of one or more attributes determines the value of one or more other attributes
Functional dependence
Attribute whose value determines another
Determinant
Attribute whose value is determined by the other attribute
Dependent
Full f….. d….. is when Entire collection of attributes in the determinant is necessary for the relationship
functional dependence
Key that is composed of more than one attribute
Composite key
Attribute that is a part of a key
key attribute
Any key that uniquely identifies each row
superkey
A superkey without redundancies
candidate key
Condition in which each row in the table has its own unique identity. All values in the PK must be unique. No nulls in the PK
entity integrity
Every reference to an entity instance by another entity instance is valid
Referential integrity
Not permitted in primary key, should be avoided in other attributes. can create problems when functions as average are used. can create logcal problems.
Nulls
C…… r……. makes the relational database work
controlled redundancy
R……. exists only when there is unnecessary duplication of attributes values
redundancy
An attribute whose values match primary key values in the related table
Foreign key
FK contains a value that refers to an existing valid tuple (row) in another relation
Referential integrity
Key used strictly for data retrieval purposes
Secondary key
for integrity rules requirement is that all …. keys entries are unique, and no nulls
primary keys
for integrity rules a ….. key may have either a null entry or a entry that matches the primary key value in a tabe to which it is related
foreign key
Special codes used to indicate the absence of some value
flags
Placed on a column to ensure that every row in the table has a value for that column
NOT NULL constrains
Restriction placed on a column to ensure that no duplicate values exist for that column
UNIQUE constraint
SELECT, PROJECT, UNION, INTERSECT , ETC ARE
Relational algebra operators
Only returns matched records from the tables that are being joined
Inner join
Yields all of the rows in the first table, including those that do not have a matching value in the second table
left outer join
Yields all of the rows in the second table, including those that do not have matching values in the first table
right outer join
Provides detailed description of all tables found within the user/designer-created database
Data dictionary
data dictionary contains m….
metadata
Detailed system data dictionary that describes all objects within the database
SYSTEM CATALOG
System catalog and data dictioanry are often used i……
interchangeably
Should be the norm in any relational database design
1:M relationship
Should be rare in any relational database design
1:1 relationship
Cannot be implemented as such in the relational model
M:N relationships
Helps avoid problems inherent to M:N relationships, includes the primary keys of tables to be linked
Composite entity (Bridge or associative entity)
Arrangement used to logically access rows in a table
index
index reference point. point to data location identified by the key
index key
index in which the index key can have only one pointer value associate with it
unique index
each index is associated with o….. o….. table
only one
