DBMS EXAM STUDY GUIDE
Relationship - Answers - association between entities
Types of relationships: - Answers - One-to-many: Each rep is associated with many
customers. Each customer is associated with a single rep
Database - Answers - structure that can store information about different categories of
information and relationships between those categories
Database Management System (DBMS) - Answers - program, or collection of programs,
through which users interact with a database; can create forms and reports
Advantages of database processing: - Answers - Getting more information from the
same amount of data
Sharing data
Balancing conflicting requirements
Controlling redundancy
Facilitating consistency
Expanding security
Increasing productivity
Providing data independence
Disadvantages of database processing: - Answers - Larger file size
Increased complexity
Greater impact of failure
More difficult recovery
Rules of a Relation - Answers - Two-dimensional table in which:
Entries are unnormalized
Each column has a distinct name (attribute name)
All values in a column are values of the same attribute
, Order of columns is immaterial
Each row is distinct
Order of rows is immaterial
Attribute - Answers - characteristic or property of an entity (field/column)
Primary Key - Answers - column or collection of columns of a table (relation) that
uniquely identifies a given row in that table
Foreign key - Answers - field(s) whose value is required to match the value of the
primary key for a second table
Relational database - Answers - collection of relations or tables
Basic relational algebra operations: - Answers - SELECT-retrieves certain rows from an
existing table (based on criteria) and saves them as a new table (includes WHERE)
PROJECT-causes only certain columns to be included in the new table (includes
OVER)
JOIN-two tables being joined
Structure of an SQL query: - Answers - SELECT-FROM-WHERE
Use of compound conditions in WHERE statements: - Answers - connecting two or
more simple conditions using one or both (AND/OR)
Use of LIKE: - Answers - include in the WHERE clause
WHERE Street LIKE "Oxford";
Wildcards: - Answers - Access:
*-collection of characters
?-any individual character
Other:
%-any collection of characters
_-any individual character
Computed Fields - Answers - field whose values you derive from existing fields (+,-,*,/)
Built-in Functions - Answers - (aggregate functions) COUNT, SUM, AVG, MAX, MIN
Relationship - Answers - association between entities
Types of relationships: - Answers - One-to-many: Each rep is associated with many
customers. Each customer is associated with a single rep
Database - Answers - structure that can store information about different categories of
information and relationships between those categories
Database Management System (DBMS) - Answers - program, or collection of programs,
through which users interact with a database; can create forms and reports
Advantages of database processing: - Answers - Getting more information from the
same amount of data
Sharing data
Balancing conflicting requirements
Controlling redundancy
Facilitating consistency
Expanding security
Increasing productivity
Providing data independence
Disadvantages of database processing: - Answers - Larger file size
Increased complexity
Greater impact of failure
More difficult recovery
Rules of a Relation - Answers - Two-dimensional table in which:
Entries are unnormalized
Each column has a distinct name (attribute name)
All values in a column are values of the same attribute
, Order of columns is immaterial
Each row is distinct
Order of rows is immaterial
Attribute - Answers - characteristic or property of an entity (field/column)
Primary Key - Answers - column or collection of columns of a table (relation) that
uniquely identifies a given row in that table
Foreign key - Answers - field(s) whose value is required to match the value of the
primary key for a second table
Relational database - Answers - collection of relations or tables
Basic relational algebra operations: - Answers - SELECT-retrieves certain rows from an
existing table (based on criteria) and saves them as a new table (includes WHERE)
PROJECT-causes only certain columns to be included in the new table (includes
OVER)
JOIN-two tables being joined
Structure of an SQL query: - Answers - SELECT-FROM-WHERE
Use of compound conditions in WHERE statements: - Answers - connecting two or
more simple conditions using one or both (AND/OR)
Use of LIKE: - Answers - include in the WHERE clause
WHERE Street LIKE "Oxford";
Wildcards: - Answers - Access:
*-collection of characters
?-any individual character
Other:
%-any collection of characters
_-any individual character
Computed Fields - Answers - field whose values you derive from existing fields (+,-,*,/)
Built-in Functions - Answers - (aggregate functions) COUNT, SUM, AVG, MAX, MIN
