University of Manitoba
Asper School of Business
3500 DBMS
Bob Travica
Chapter 1
Introduction
Based on G. Post, Database Management Systems
Updated 2016
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Basic Concepts of Database Systems
 Database is
 A collection of data organized in some way
 grouped on what they refer to (business), and on data types
(technology)
 relationships between pieces of data
 Data = symbols for recording and communication (e.g., customer ID and name)
 Example: Think of records (paper, electronic) describing employees.
EmployeeID
LastName
FirstName
Phone
Number
Text
Text
Number
 The organization of data is explained by metadata.
 Employee is a class of data (what data refer to), which has x number of
attributes, and each attribute belongs to a specific data type (text, numeric…).
More 
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Basic Concepts
 Database Management System (DBMS)
 Software for creating databases, storing & retrieving data, creating
user interface (forms), creating reports, and administering a DB
system (security, access, etc.).
 DBMS Product (a specific DBMS software; same as “DBMS Brand”).
 Database System (DBMS Application, Application)*:
 An implementation of a DBMS product including one or more
databases, logic (business rules), some code, and user interface.
 Broader meaning: Supporting various information needs.
 An information system that results from “applying” a DBMS or a
database.
 Narrower meaning: Supporting specific information needs.
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File (Processing) Systems vs. DB systems
(DBS)
 Historical, but also a frequent shortcut today (e.g., Excel used as
a FPS to simulate DBS)
 File Processing Systems:
 Data files and program files (code) that work on data files, or
 Data and code in the same file
 Separate code (functionality) for data input, modification,
retrieval, & deletion.
 Data files are closely coupled with programs that define
metadata - tight coupling reducing design flexibility (changes).
More 
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File (Processing) Systems vs. DB systems
DBS are:
 Higher on retrieval capabilities
 Lower redundancy, higher data integrity
 Data independent from programs (code); looser coupling –
changes in data and code less restricted
 Better security and management of concurrent access to
database
 Significantly lower development and maintenance cost
 But keep in mind: Excel’s enduring popularity in companies.
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Modifying Data in DBS
-- Data-Program independence
 Add cell tel. number to
employee table
 Open table template
 Add data element
 Existing reports, queries,
code will not crash although
need to be modified to
output new data – looser
coupling
Field Name
Data Type
Description
EmployeeID
TaxpayerID
LastName
FirstName
...
Phone
...
Number
Text
Text
Text
Autonumber..
Federal ID
Text
Phone Number
CellPhone
Text
Cell Phone No.
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DB System Components
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Database Engine:
DBMS
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Database
• CRUD* operations & Data Dictionary
• Concurrency & Lock Manager
• Recovery Manager
• Disk Space Manager
Query Processor
Form
Builder
Report
Writer
Application
Generator
Data & Metadata
Management
Security
Management
Retrieval
Input/Output;
User Interface
System development
tools **
*CRUD= Create, Read, Update, Delete. Note that the Post book mixes up term “database” with “data” and “application”.
** In the past, this was a DBMS module for automating creation of forms & reports. Today, App. Generator can create all
parts of a DB system, so better name is DBS Generator. See.
Form
Builder
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Creating Outputs via Report Writer
Database
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3
Database Engine
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2
Query Processor
1
Report Writer
6
Output: Report
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Relational Database Standard
 “Relation” = table, a logical view of the data
structure for storing data.
An example of Table (Sale) created in Oracle.
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Examples of Relational DBMS Products

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


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Oracle
Sybase
Informix (Unix)
DB2, SQL/DS (IBM)
Access, SQL Server (Microsoft)
Many limited to PC (MS Access, dBASE, Paradox, …)
Open source: MySQL (more)
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Hierarchical Database
• First commercial standard (IBM’s IMS)
• Still used in legacy systems
Customers
file folders which contain
orders which contain items
Entry point
Customer
XYZ
pointers
Order 2
Order 1
Order
files
pointers
Item A
Items
Item# ItemName
998 Dog Food
764 Cat Food
Quantity
12
11
Item B
Item A
Item C
To retrieve how many of item A are sold, start
at the top from Customer. Then all nested data
are retrieved top-down and left-right.
Different data models needed for different
retrieval tasks (e.g., Order at the root) =>
high data redundancy in hierarchical DBS!
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Network Database
Entry point
Customer
XYZ
Order 1
Relationships between records also
supported by pointers;
complex programming.
Order 2
Entry points
Item A
Item B
Item C
One data model supports different retrieval paths (by
customer, order, item).
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Relational Database
Primary Key (PK, Key)
Foreign Key (FK)
Customer(CustomerID, Name, …)
Order(OrderID, CustomerID, OrderDate, …)
ItemOrdered(OrderID, ItemID, Quantity, …)
Item(ItemID, Description, Price, …)
• Data organized as logical tables, consisted of rows (records) and
columns (attributes), and connected via key attributes.
• Possible to retrieve almost any combination of rows and columns,
and a specific piece of data within a row.
• Pointers transparent to developers, just need to specify Primary
Key (PK)—Foreign Key (FK) relationships.
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Object DB & Object-Relational DB Systems
•
•
•
•
Extends data types and methods over relational DB.
Takes advantages of OO capabilities (e.g., inheritance).
Pure ODB rare (storage of objects with CRUD code); not fully formalized
as relational DB systems are.
ORDB is a standard. The basic storage is usually a relational database
combined with a storage of non-alphanumeric objects (e.g., images).
Order
OrderID
CustomerID
…
NewOrder
DeleteOrder
…
Customer
CustomerID
Name
…
Add Customer
Drop Customer
Data
Change Address…
Procedures (behavior,
methods) for processing
data.
Government
Customer
Corporate
ContactName
ContactPhone
ContactName
Discount, …
ContactPhone
…
NewContact
AddNewContact
Inheritance in Generalization/Specialization relationship
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 Objects are created in main memory according to class diagram
(logical design) and business rules; many designs, same databases
 Objects are populated by data from the beck-end relational
databases (data access layer in system sequence diagrams).
Extended data and method capabilities in objects.
 System operations are performed by objects
 Postgres/PostgreSQL, Illustra (then IBM), Omniscience (then
Oracle)
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