• Study Resource
• Explore

# Download Kroenke-DBP-e10-PPT-Chapter01

Survey
Was this document useful for you?
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

SQL wikipedia, lookup

Clusterpoint wikipedia, lookup

Open Database Connectivity wikipedia, lookup

Relational model wikipedia, lookup

Database model wikipedia, lookup

Microsoft Jet Database Engine wikipedia, lookup

Concurrency control wikipedia, lookup

Extensible Storage Engine wikipedia, lookup

Database wikipedia, lookup

Entity–attribute–value model wikipedia, lookup

Relational algebra wikipedia, lookup

ContactPoint wikipedia, lookup

Oracle Database wikipedia, lookup

IMDb wikipedia, lookup

Transcript
```Thomas Connolly
and Carolyn Begg’s
Database Systems:
A Practical Approach to Design,
Implementation, and Management
Chapter 4 Part One:
Relational Terminology
Of course, we are still using Kroenke’s slide format!
1-1
Today’s Objectives
• To understand the terminology of the
relational model.
• Properties of database relations
• The meaning of entity integrity and
referential integrity
1-2
The Relational Database Model
• The dominant database model is the
relational database model – all current
major DBMS products are based on it
• Created by IBM engineer E. F. Codd in
1970
• It was based on mathematics called
relational algebra
DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition
© 2006 Pearson Prentice Hall
1-3
The Relational Model
• “The Relational Database Management
System(RDBMS) has become the dominant
data-processing software in use today, with
estimated sales of between US\$15 billion and
US\$20 billion per year,…, and growing at a rate
of possibly 25% per year.” Connolly, Begg. P. 70
• A relation is viewed as a two dimensional table
of data where columns are the attributes of the
data and rows, or tuples, contain records of the
user data.
• Each row contains one piece of data per column.
1-4
Database Relations
• Relation schema: A named relation
defined by a set of attribute and domain
pairs. [p.76]
• Relational database schema: A set of
relation schemas, each with a distinct
name. [p. 76]
1-5
Properties of Relations
• The relation has a name that is distinct from all
other relation names in the relation schema
• Each cell of the relation contains exactly one
single value
• Each attribute has a distinct name
• The values of an attribute are all from the same
domain
• Each tuple is distinct
• The order of attributes has no significance
• The order of tuples has no significance
• [p.77]
1-6
Relational Keys
• Superkey: An attribute, or set of attributes, that
uniquely identifies a tuple within a relation.
• Candidate key: A superkey such that no proper
subset is a superkey within the relation.
• Primary key: The candidate key that is selected
to identify tuples uniquely within the relation.
• Foreign key: An attribute, or set of attributes,
within one relation that matches the candidate
key of some (possibly the same) relation.
• [p.80]
1-7
Relational Integrity
• Domain constraints form restrictions on the set
of values allowed for the attributes of relations.
• Null: Represents a value for an attribute that is
currently unknown or is not applicable for this
tuple.
• Entity Integrity: No attribute of the primary key
can be null.
• Referential Integrity: If a foreign key exists in a
relation, either the foreign key value must match
a candidate key value of some tuple in its home
relation or the foreign key value must be wholly
null.
1-8
Thomas Connolly
and Carolyn Begg’s
Database Systems:
A Practical Approach to Design,
Implementation, and Management
End of Presentation
Of course, we are still using Kroenke’s slide format!
1-9
```
Related documents