Introduction
• Database design
• Process of determining the particular tables and columns that
comprise a database
• One must understand:
• Database concepts
• Process of normalization

Database Concepts
• Entity
• Attribute
• Relationship
• Functional dependence
• Primary key

Relational Database
• A collection of tables
• Tables in KimTay Pet Supplies Database
• SALES_REP
• CUSTOMER
• INVOICES
• INVOICE_LINE
• ITEM

Entities, Attributes, and Relationships (1 of 4)
• Entity (like a noun)
• A person, place, thing, or event
• Attribute
• Property of an entity
• Relationship
• Association between entities
• One-to-many relationship
• One sales representative (sales rep) is related to many customers
• Implemented by having common columns in two or more tables
• REP_ID is a column in the SALES_REP table as well as the
CUSTOMER table
• Repeating groups
• Multiple entries in an individual location

Figure 2-2: Table with Repeating Groups
INVOICES
INVOICE_NU
M
INVOICE_D
ATE
CUST_ID ITEM_ID QUANTI
TY
QUOTED_PRI
CE
14216 11/15/2021 125 CA 75 3 $37.99
14219 11/15/2021 227 AD 72 2 $79.99
NA NA NA DT 12 4 $39.99
14222 11/16/2021 294 LD 14 1 $47.99
14224 11/16/2021 182 KH 81 4 $18.99
14228 11/18/2021 435 FS 42 1 $124.99
NA NA NA PF 19 1 $74.99
14231 11/18/2021 125 UF 39 2 $189.99
14233 11/18/2021 435 KH 81 1 $19.99
NA NA NA QB 92 4 $109.95
NA NA NA WB 49 4 $74.95
14237 11/19/2021 616 LP 73 3 $54.95

Figure 2-3: INVOICES Table without Repeating Groups
INVOICES
INVOICE_
NUM
INVOICE_DAT
E
CUST_ ID ITEM_ID QUANTITY QUOTED_PRIC
E
14216 11/15/2021 125 CA 75 3 $37.99
14219 11/15/2021 227 AD 72 2 $79.99
14219 11/15/2021 227 DT 12 4 $39.99
14222 11/16/2021 294 LD 14 1 $47.99
14224 11/16/2021 182 KH 81 4 $18.99
14228 11/18/2021 435 FS 42 1 $124.99
14228 11/18/2021 435 PF 19 1 $74.99
14231 11/18/2021 125 UF 39 2 $189.99
14233 11/18/2021 435 KH 81 1 $19.99
14233 11/18/2021 435 QB 92 4 $109.95
14233 11/18/2021 435 WB 49 4 $74.95
14237 11/19/2021 616 LP 73 3 $54.95

Entities, Attributes, and Relationships (2 of 4)
• Relation is a two-dimensional table
• Entries in the table are single-valued
• Each column has a distinct name
• All values in a column match this name
• Each row is distinct
• Order of the rows and columns is immaterial

Entities, Attributes, and Relationships (3 of 4)
• Use shorthand representation to show tables and
columns in a relational database
• For each table, write the name of the table and then within
parentheses list all of the columns in the table
SALES_REP (REP_ID, FIRST_NAME, LAST_NAME, ADDRESS,
CITY, STATE, POSTAL, CELL_PHONE, COMMISSION, RATE)
CUSTOMER (CUST_ID, FIRST_NAME, LAST_NAME, ADDRESS,
CITY, STATE, POSTAL, EMAIL, BALANCE, CREDIT_LIMIT, REP_ID)
INVOICES (INVOICE_NUM, INVOICE_DATE, CUST_ID)
INVOICE_LINE (INVOICE_NUM, ITEM_ID, QUANTITY,
QUOTED_PRICE)
ITEM (ITEM_ID, DESCRIPTION, ON_HAND, CATEGORY, LOCATION,
PRICE)

Entities, Attributes, and Relationships (4 of 4)
• Database management system (DBMS)
• Set of programs that allows users to store, manipulate, and
retrieve data efficiently
• Requires columns with duplicate names to be qualified to avoid
confusion
• Reference the REP_ID column in the CUSTOMER table as
CUSTOMER.REP_ID
• Reference the REP_ID column in the SALES_REP table as
SALES_REP.REP_ID

Functional Dependence
• A column, B, is functionally dependent on another
column, A, if a value for A determines a single value for B
at a point in time
• B is functionally dependent on A
• A → B
• A functionally determines B
• Cannot be determined from sample data
• One must know user’s policies

Figure 2-4: SALES_REP Table with a PAY_CLASS Column
SALES_REP
REP
_
ID
FIRST
_
NAME
LAST
_
NAME
ADDRE
SS
CIT
Y
STA
TE
POST
AL
CEL
L_
PHO
NE
COMMI
SSION
PAY_
CLAS
S
RAT
E
05 Susan Garcia 42
Mountai
n Ln
Cod
y
WY 8241
4
307-
824-
1245
$12,743
.16
1 0.04
10 Richar
d
Miller 87 Pikes
Dr
Ral
ston
WY 8244
0
307-
406-
4321
$20,872
.11
2 0.06
15 Donna Smith 312 Oak
Rd
Po
well
WY 8244
0
307-
982-
8401
$14,912
.92
1 0.04
20 Daniel Jacks
on
19
Lookout
Dr
Elk
Butt
e
WY 8243
3
307-
883-
9481
$0.00 1 0.04

Primary Key
• Unique identifier for a table
• Column A (or a collection of columns) is the primary key
for a table if the following is true:
• Property 1
• All columns in the table are functionally dependent on A
• Property 2
• No subcollection of the columns in A (assuming that A is a collection of
columns and not just a single column) also has Property 1

Primary Key: Shorthand Representation
• A table’s primary key can be indicated by underlining the
column or collection of columns that comprise the
primary key
SALES_REP (REP_ID, FIRST_NAME, LAST_NAME, ADDRESS,
CITY, STATE, POSTAL, CELL_PHONE, COMMISSION, RATE)
CUSTOMER (CUST_ID, FIRST_NAME, LAST_NAME, ADDRESS,
CITY, STATE, POSTAL, EMAIL, BALANCE, CREDIT_LIMIT, REP_ID)
INVOICES (INVOICE_NUM, INVOICE_DATE, CUST_ID)
INVOICE_LINE (INVOICE_NUM, ITEM_ID, QUANTITY,
QUOTED_PRICE)
ITEM (ITEM_ID, DESCRIPTION, ON_HAND, CATEGORY, LOCATION,
PRICE)

Database Design
• Based on a set of requirements that the database must
support
• Requirements are gathered through a process known as
systems analysis

Design Method
• Read the requirements, identify the entities (objects)
involved, and name the entities
• Identify the unique identifiers for the entities identified in
the previous step
• Identify the attributes for all the entities
• Identify the functional dependencies that exist among the
attributes
• Use the functional dependencies to identify the tables by
placing each attribute with the attribute or minimum
combination of attributes on which it is functionally
dependent
• Identify any relationships between tables

Database Design Requirements
• Requirement for KimTay Pet Supplies involves storing
information pertaining to:
• Sales reps
• Customers
• Items
• Invoices
• Invoice lines
• Conditions for invoice lines
• There is only one customer per invoice
• On a given invoice, there is at most one line item for a given item
• The quoted price may differ from the actual price

Database Design Process Example: KimTay Pet
Supplies (1 of 2)
• Identify the entities, and name them
• SALES_REP, CUSTOMER, ITEM, and INVOICES
• Review the data, and determine the unique identifier for
each entity
• REP_ID, CUST_ID, ITEM_ID, and INVOICE_ NUM
• Assign appropriate names to the specific attributes in
each of the requirements
• Identify functional dependencies based on associations
of attributes with unique identifiers

Database Design Process Example: KimTay Pet
Supplies (2 of 2)
• Use the established functional dependencies to create
tables for each of the requirements
• Examine the tables, and identify common columns
among them to arrive at a list of relationships

Diagrams for Database Design
• Entity-relationship (E-R) diagram is an illustration in
which:
• Rectangles represent entities (tables)
• Lines represent relationships
• Some styles of E-R diagrams use arrows or crow’s foot
• Original style of E-R diagrams
• Relationships are indicated in diamonds that describe the
relationship
• The number 1 indicates the one side of the relationship, and the
letter “n” represents the many side of the relationship

Figure 2-13: E-R Diagram for the KimTay Pet
Supplies Database with Rectangles and Arrows

Figure 2-14: E-R Diagram for the KimTay Pet
Supplies Database with Crow’s Foot

Figure 2-15: E-R Diagram for the KimTay Pet
Supplies Database with Named Relationships

Objectives
• Create and run S Q L commands
• Create and activate a database
• Create tables
• Identify and use data types to define columns in tables
• Understand and use nulls
• Add rows to tables
• View table data
• Correct errors in a table
• Save S Q L commands to a file
• Describe a table’s layout using S Q L

Introduction
• Structured Query Language (S Q L)
• One of the most popular and widely used languages for retrieving
and manipulating database data
• Developed in the mid-1970s under the name SEQUEL
• Renamed S Q L in 1980
• Used by most database management systems (DBMS)

Creating and Running S Q L Commands
• Can be done by using a DBMS that supports S Q L to
accomplish tasks
• My S Q L 8.0 (My S Q L Community Server 8.0.18)
installation
• Suggested setup types: Developer default type and full type
• Both include the installation of the My S Q L Workbench
• My S Q L Workbench contains:
• Powerful tools that allow developers and database administrators to
visually design, develop, and administer My S Q L databases
• An S Q L editor that is used throughout the text to enter commands
and view the results of the commands entered
• Users should make sure they remember the password selected
during installation

Using My S Q L Workbench
• Run My S Q L Workbench 8.0 C E app after My S Q L 8.0
is installed
• Access the main My S Q L Workbench environment for
the listed connection via the server created during
installation
• By clicking the available connection box listed on the My S Q L
Workbench opening window and then submitting the password
• Simplify the main window to give more room for the
Query pane and Output pane
• By hiding Navigation pane and My S Q L Additions pane

Figure 3-1: My S Q L Workbench Opening Window

Figure 3-2: Entering Password for Server

Figure 3-3: Main My S Q L Workbench Environment

Figure 3-4: Outcome of Hiding the Navigator and S Q L
Additions Panes

Entering Commands
• Commands
• Followed by a semicolon
• Semicolon ends a statement in S Q L
• Entered into the My S Q L Workbench S Q L editor
• Microsoft has a specific system of identifying keywords
• Executed by selecting Execute Current Statement or Execute (All
or Selected) from the Query menu
• Displays a result grid between the query pane and output pane
▶ Result grid and details from output pane can be cleared
• History of processing commands can be accessed
• Cleared by highlighting and deleting them

Figure 3-5: Syntax of the SHOW DATABASES
Command

Figure 3-6: Enter SHOW DATABASES Command

Figure 3-7: Execute the Query

Figure 3-8: Outcome of SHOW DATABASES
Command

Figure 3-9: To Clear Results of the SHOW
DATABASES Command

Creating a Database (1 of 2)
• Objects within a database have identifiers, or names,
associated with them
• DBMS rules for naming identifiers vary
• General guidelines for naming identifiers when using a
DBMS
• The identifier name:
• Cannot exceed 30 characters
• Must start with a letter
• Can contain letters, numbers, and underscores (_)
• Cannot contain spaces

Creating a Database (2 of 2)
• Steps involved
• Enter the command keyword followed by the desired name of
database and end with semicolon
• Execute the command
• Execute the command to list databases
• Results in six internal databases and one additional database that was
created with the desired name

Changing the Default Database
• Known as activating or using the database
• Default database must be set to the database one wants
to work with
• Default database is the one to which all subsequent commands
pertain
• Activate the default database
• By executing the USE command followed by the name of the
database
• Tables can be added to the database after it has been
activated

Figure 3-10: Syntax of the CREATE DATABASE
Command

Figure 3-11: Enter SHOW DATABASES Command

Figure 3-12: Outcome of SHOW DATABASES
Command after Creating the KimTay Database

Figure 3-13: Syntax of the USE Command

Figure 3-14: Enter USE Command to Activate the
KIMTAY Database

Creating a Table (1 of 2)
• Describe the layout of the table in the database
• Use the CREATE TABLE command followed by:
• Table name
• Names and data types of the columns in the table
• Data types: Define the type of data and the number of characters
or digits stored in each column of data

Figure 3-15: CREATE TABLE Command to Create
the SALES_REP Table

Creating a Table (2 of 2)
• Commands are free format
• No rules stating specific words in specific positions
• Commands are not case sensitive
• Exception: Use the correct case when inserting values into a table

Oracle Figure 3-1: CREATE TABLE Statement to
Create SALES_REP Table Using Oracle

S Q L Server Figure 3-1: CREATE TABLE Statement
to Create SALES_REP Table Using S Q L Server

Figure 3-17: Outcome of SHOW TABLES Command
Listing the Tables in the KIMTAY Database

Correcting Errors in S Q L Commands
• Use the same techniques that you might use in a word
processor
• Make changes and click the Run button to execute the
command again

Dropping a Table
• Errors in tables can be corrected by dropping (deleting)
and starting over
• Useful when a table is created before errors are
discovered
• Command is followed by the table to be dropped and a
semicolon
• Data in the table will also be deleted

Using Data Types
• For each column, the type of data must be defined
• Common data types
• CHAR(n)
• VARCHAR(n)
• DATE
• DECIMAL(p,q)
• INT
• SMALLINT

Using Nulls (1 of 2)
• A special value to represent a situation when the actual
value is not known for a column
• Can specify whether to allow nulls in the individual
columns
• Should not allow nulls for the primary key column
• Use the NOT NULL clause in a CREATE TABLE
command to indicate columns that cannot contain null
values
• Default is to allow null values
• If a column is defined as NOT NULL, system will reject
any attempt to store a null value there

Using Nulls (2 of 2)
CREATE TABLE SALES_REP
(
REP_ID CHAR (2) PRIMARY KEY,
FIRST_NAME CHAR (20) NOT NULL,
LAST_NAME CHAR (20) NOT NULL,
ADDRESS CHAR (20),
CITY CHAR (15),
STATE CHAR (2),
POSTAL CHAR (5),
CELL_PHONE CHAR (12),
COMMISSION DECIMAL (7, 2),
RATE DECIMAL (3, 2)
);

Adding Rows to a Table
• INSERT command
• Type INSERT INTO followed by the name of the table
• Type VALUES followed by specific values in parentheses
• Type Values for character columns in single quotation marks
• To add new rows, modify the previous INSERT command
• Use the same editing techniques as those used to correct errors

Figure 3-22: INSERT Command Executed for the
First Record in the SALES_REP Table

Inserting a Row That Contains Nulls
• Use a special format of INSERT command to enter a null
value in a table
• Identify the names of the columns that accept non-null
values and then list only the non-null values after the
VALUES command

Figure 3-30: INSERT Command Executed for the Fifth Record in the
SALES_REP Table Containing Null Values

Viewing Table Data
• Use the SELECT command
• Displays all the rows and columns in a table
• Display all the rows and columns in the SALES_REP
table
• SELECT * FROM followed by the name of the table
• End with a semicolon
• In Oracle
• Enter the statement followed by slash (/)
• In S Q L Server
• Enter SELECT statement in the Query Editor
window

Correcting Errors in a Table
• UPDATE, DELETE, and INSERT
• UPDATE command is used to change a value in a table
• DELETE is used to delete a row
• INSERT is used to add a row

Figure 3-34: Using an UPDATE Command to Change a
Value

Figure 3-35: Using a SELECT Command to View a Table

Figure 3-37: Using the DELETE Command to Delete a Row

Saving S Q L Commands (1 of 6)
• Allows the use of commands repeatedly without retyping
them
• Commands are saved in a script file or script
• Text file with .s q l extension
• Script repository
• Available in some database management systems such as Oracle
• Specific location on local drive is used to download scripts

Saving S Q L Commands (2 of 6)
• To create and save a script in My S Q L
• Enter the command, or commands, that would comprise the script
in the query pane
• On the My S Q L Workbench main menu, click on the File menu
and select the Save Script As option
• Navigate to a location in the file system where the file has to be
saved
• Enter a name for the script in the File name
• Click the Save button
• To view, edit, or run a script in My S Q L
• On the My S Q L Workbench main menu, click on the File menu
and select Open S Q L Script
• Navigate to the location in the file system where the script is saved

Saving S Q L Commands (3 of 6)
• Select the script and click Open
• Selected script is now in a new tab in the query pane without any
change in the name of the script and can now be edited or run by
choosing one of the two options below:
• Execute by clicking Query on the My S Q L Workbench main menu
and selecting the appropriate execute option
• In the Run S Q L Script dialog box, select the Default Schema Name
from the drop-down menu and click Run
▶ Click on Close to close the Run S Q L Script dialog box after the results are
displayed
• To delete a script in My S Q L
• Navigate to the location in the file system where the script is saved
• Delete the file containing the script

Saving S Q L Commands (4 of 6)
• To create a script file in Oracle S Q L Developer
• Load the Oracle S Q L Developer tool
• Enter query statement to be stored and execute it
• Click the Save button and then enter a name for the script
• To view, edit, or run an existing script in Oracle S Q L
Developer
• Load Oracle S Q L Developer and double click on Database
Connection
• Click the Open File button on the toolbar
• Navigate to the folder containing the script file and then click the
Open button in the Open File dialog box
• Make edits and click the Save button to save changes
• To run a script, click the Execute button

Saving S Q L Commands (5 of 6)
• To create a script file in S Q L Server
• Load S Q L Server Management Studio and then click the Connect
button in the Connect to Server dialog box
• Open the appropriate database and then click the New Query
button
• Type the command or commands to save in the script
• When necessary, click the Execute button to execute the commands
saved in the script
• Click the Save button and then enter a name for the script

Saving S Q L Commands (6 of 6)
• To view, edit, or run an existing script in S Q L server
• Load S Q L Server Management Studio and then click the Connect
button in the Connect to Server dialog box
• Open the appropriate database and then click the New Query
button
• Click the Open File button on the toolbar
• Navigate to the folder containing the script file and then click the
Open button in the Open File dialog box
• Click the Save button to save any changes made
• Click the Execute button to run the script

Creating the Remaining Database Tables
• Execute appropriate CREATE TABLE and INSERT
commands
• Save these commands as scripts
• Separate multiple commands in a script file with a
semicolon

Describing a Table
• Involves using the DESCRIBE command
• DESC in also accepted in My S Q L and Oracle
• SP_COLUMNS in S Q L Server

Figure 3-47: DESCRIBE Command for the SALES_REP Table

Summary (1 of 2)
• Use the CREATE TABLE command to create tables
• Use the DROP TABLE command to delete a table
• CHAR, VARCHAR, DATE, DECIMAL, INT, and
SMALLINT are commonly used data types
• Null value is used when an actual value for a column is
unknown, unavailable, or not applicable
• Use the NOT Null clause to identify columns that cannot
accept a null value
• Use the INSERT command to add rows in a table
• Use the SELECT command to view data in a table

Summary (2 of 2)
• Use the UPDATE command to change the value in a
column
• Use the DELETE command to delete a row from a table
• S Q L commands in a script file can be saved in My S Q
L, Oracle, and S Q L Server
• The DESCRIBE command in My S Q L and Oracle can
be used to display a table’s structure and layout, and
SP_COLUMNS in S Q L Server