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MySql In Action
Step by step method to create
your own database
What is next?
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Having convinced that MySql is a strong tool to
develop databases, you are wondering if you can
use it to develop your own business.
This is the story.
– You want to open a small video rental in Seattle. You are
thinking to create a small database to keep track what kind of
films that you have, how long the films are checked out, and
how much money that a customer has to pay for renting a film .
– Since you already know that MySql is easy to use, you will use it
for developing your own database.
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Database Structure for Video Rental I
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After spending some time, you come up with the
following structure of the database that you need
for your small video rental.
– Customers
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customerID ( int ) => Primary Key
firstName ( VarChar(20) )
lastName ( VarChar(20) )
address
( VarChar(20) )
– Rentals
• movieID
• title
• copyNum
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( int ) => Primary Key
( VarChar(20) )
( int )
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Database Structure for Video Rental II
– CheckOut
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•
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•
•
•
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entryID
customerID
movieID
checkOutDate
duration
cost
( int ) => Primary Key
( int )
( int )
( date/time )
( int )
( double )
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Connecting To MySql
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Until this point, you are ready to create tables to
implement your database.
The first step that you have to do is to connect to
MySql by using your favorite tool, such as Telnet
or x-window.
I assume that you already contacted the database
administrator to create a blank database which is
called “video_rental”.
On the prompt, type in mysql -p video_rental
– ‘-p’ option is used to tell MySql that you will use password to
connect to your database.
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Connecting To MySql (Cont….)
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After you logon to MySql, you should get similar
result as the following:
Note:
– I use x-window to logon to MySql
– On the prompt, it displays “ffaizal@cochise”
• cochise is the name of the server that I use, and
• ffaizal is my login name in that server.
– You should get similar prompt when you logon to MySql.
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Creating Customers table
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The next step is to create tables on the
video_rental database.
The First table that you will create is Customers
table.
To create that table, you need to use create table
command.
In this case, you should use
create table Customers (customerID int unsigned
auto_increment primary key, firstName varchar(20) not null
default ‘N/A’, lastName varchar(20) not null default ‘N/A’,
address varchar(30) not null default ‘N/A’);
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Creating Customers table (Cont….)
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If you want to know and check the table that you
just created, you can use show command.
– I used show columns from Customers;
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Creating Customers table (Cont….)
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Note:
– customerID is a primary key. I declared it as an unsigned
integer with auto increment so that I can always get the unique
number.
– For the rest of the table, I declared them as variable
characters with a default value N/A.
– In all columns, I will not allow them to have null as value.
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Creating Rentals table
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The second table that you should create is Rentals
table.
Following the syntax from the previous table
creation, you should come up with the following
command:
create table Rentals (movieID int unsigned auto_increment
primary key, title varchar(20) not null default ‘N/A’, copyNum
int unsigned not null);
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Creating Rentals table (Cont….)
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Note:
– movieID is a primary key. I declared it as an auto-incremented
unsigned integer.
– Title is a variable character with default value ‘N/A’.
– copyNum is an integer with 0 as its default value.
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Creating CheckOut table
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CheckOut table is the last table that you need to
create.
Following the syntax from the previous slides, the
command will be as the following:
create table CheckOut(entryID int unsigned auto_increment
primary key, customerID int unsigned not null, movieID int
unsigned not null, checkOutDate datetime not null default
'N/A', duration int unsigned not null, cost double unsigned not
null);
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If you succeeded in creating the table, you will get
the same result as the one shown on the next
page.
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Creating CheckOut table (Cont….)
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Note:
– entryID is used as a primary key, instead of customerID and
movieID. MySql does not allow more than two primary keys on
the same table.
– The rest of the table should be clear from the above
screenshot.
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Checking Your Database
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The quick way to check all tables that you have
created is by using the show tables command.
Congratulation…. You have successfully created
three tables in the video_rental database.
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Inserting data into the tables
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After you have created tables in video_rental
database, it’s time for you to input the data.
Suppose that you have invested some money to buy
five copies of “StarWars” and you want to store
this information into your Rentals table.
How do you do that???
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Inserting data into the tables (Cont.)
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Use insert command.
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The command should look like the following:
– insert into Rentals (title, copyNum) values ('StarWars', 5);
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Since the movieID is auto-increment integer, I do
not have to explicitly give a value. It is done
automatically for you.
If the insertion is successful, you will have the
similar result as the one on the next slide.
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Inserting data into the tables (Cont.)
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To see the entry in the table, you can use “select *
from Rentals;”.
– * means that you want to see all available columns in the table
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Remember to use ‘ or “ at the beginning and at the
end of the string values.
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All entries are already inserted
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Congratulation….
To shorten your time, all the data insertions are
already done for you.
Customers table
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All entries are already inserted (Cont.)
Rentals table
CheckOut table
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Deleting data from a table
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You can delete an entry from a table by using
delete command.
Suppose that you inserted a wrong data in
CheckOut table as shown at the last row of the
following table.
– There is no customer with ID# 4 and there is not movie with
ID# 4 as well.
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Deleting data from a table (Cont.)
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I used the following query to delete the last row:
– delete from CheckOut where entryID = 4;
– You can use different condition on where clause, such as
customerID = 4.
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Deleting a table from a database
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In addition to record deletion command, MySql
also provides a command to delete a table from a
database.
Use drop table command to delete a table.
Suppose that you want to delete a table whose
name is service, you can use the following
command:
– drop table service;
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Deleting more than one table
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You can also use the drop table command to delete
more than one table at the same time by cascading
the table names.
Suppose that in addition to service, you also want
to delete tables pay and time. You can delete them
by using:
– drop table service, pay, time;
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Select-Form-Where query
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Like almost all SQL query, MySql uses Select,
From, and Where syntax to retrieve some
information form the database.
The Form clause is usually used to indicate which
relation(s) to which the query refers.
The Where clause is consist of the condition in
which tuples must satisfy.
The Select clause is consist of attribute(s) of
tuples that match the condition(s).
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Select-Form-Where query (Cont.)
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Suppose that you want to retrieve the information
about your customer whose last name is Doe.
The proper query will be
select *
from Customers
where lastName = ‘Doe’;
Note: * means that you want to retrieve all information
about the customer whose last name is Doe.
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Select-Form-Where query (Cont.)
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The result of the query is shown below.
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