data processed by summing, ordering, averaging, grouping, comparing or other similar operations.
means of uniquiely identifying each row in a relation/table
only one per relation
may be a composite key
ideal primary key is short, numeric and never changes
a primary key containing numbers that are automatically generated and assigned in the database itself
What is the difference between a form and a report?
one is input and one is output
a key that consists of two or more columns
a key that determines all other columns (attributes) in a relation
a combination of one or more columns that is used to identify rows in a relation
occurs when the value of one (set of) attribute(s) determines the value of a second (set of) attribute(s)
a determinant of a functional dependency that consists of more than one attribute
recorded facts and numbers
knowledge derived from data
data presented in a meaningful context
data processed by summing, ordering, averaging, grouping, comparing, etc.
has rows and columns like a spreadsheet
breaks databases into related things
stores a characteristic common to all rows
a row containing (recording) data for a specific instance
an occurance of a thing
contains data about a particular occurance or instance of a thing of interest
stores data and relationships
records data in such a way that we can produce information from the data
What are the four typical components of a database system?
What's the fifth?
users, database application, database management system (DBMS), and the database
Structured Query Language (SQL)
Structured Query Language - an internationally recognized standard language that is understood by all commercial DBMS products.
Database management system - a computer program used to create, process, and administer the database.
a set of one or more computer programs that serves as an intermediary between the user and the DBMS
Basic functions of Application Programs:
create and process forms
process user queries
create and process reports
execute application logic
tells the database what the user needs to communicate - entry or input
where the database is asked a question and it returns an answer
the answer to a query in an unformatted display - generally columnar
answer generated by a query but instead of coming out in a result set, it comes out in a formatted display - through a report generator
a self-describing collection of integrated tables. Tables are integrated because they store data about the relationships between the rows of data, self-describing because it stores a description of itself.
Referential integrity constraints
rules that are enforced by the DBMS
Functions of a DBMS
create supporting structures (e.g., indexes)
read database data
modify (insert, update, or delete) database data
maintain database structures
perform backup and recovery
the number of people hitting the database at the same time
The biggest issue with enterprise DBMS is:
concurrency - the number of people hitting the database at the same time (e.g. one user's work interfering with another user's work)
Examples of DBMS products:
Microsoft Access - low end not for professionals
tables that store both data and the relationships among the data
data about data - tables contained within a database that describe the data within that database (table names, number of columns, primary keys, etc.)
tables of user data
What are the three types of database design?
1. From existing data
2. New systems development
3. Database redesign
some identifiable thing that users want to track (e.g. customers, computers, sales, etc.)
provides the content that goes into the relation
the structure that will become the table in the database
Rules about relations:
rows contain data about an entity
columns contain data about attributes of the entity
all entries in a column are of the same kind
each column has a unique name
cells of the table hold a single value
the order of the columns is unimportant
the order of the rows is unimportant
no two rows may be identical
In order to have a referential integrity we have to have a minimum of __ tables.
2 tables = 1 referential integrity constraint
3 tables = 2 referential integrity constraints
4 tables = 3 referential integrity constraints etc.
A value cannot exist in a ________ key if it does not exist in the _______ key.
A value cannot exist in a foreign key if it does not exist in the primary key.