Ch.8a Mysql Database

8/9/2019 Ch.8a Mysql Database

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MySQL Database Management System

By Tony Chun-Kuen WONG

8/03/2010

Problems with Data in file

To store data into a file Difficult to retrieve the data

No standard format for the data stored in the file

Difficult to handle data within same category

Difficult to search a specific data within a file

..

retrieval of large amount of data. Amazon.com

Internet banking


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There are different ways to store and manipulate data:

A simple text file-- . .

A relational database (e.g. Oracle, Sybase, MySQL, ACCESS)

For large amount of data and complex structure (i.e.,

large number of tables related to one another),

RDBMS is a better choice.

More flexible

Better access control (granting different privileges to different users

for the same database, table, or even attribute)

Examples

Show catalogue using products databases

Recognize the user using membership database

Dynamic Posting by examining users characteristics and

posting appropriate information that retrieve data fromrelated database.


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MySQL DBMS

The RDBMS that we use is called MySQL

MySQL DBMS is a Client-Server application

A database server program is running on a server machine In our case, the server machine is ism

The database server program is call mysqld

and updates

The server program wait for requests from clients

Client use SQL to request data

The clients can be run on the same machine as the server,or on other mach nes on a networ

Accessing Database Server by a Client

Database Server Machine (Wisdom)isem03

MySQL

Database

Database

INTERNET

SQL

Server(mysqld)DATA

Database Server Machine (Wisdom)isem03

MySQL

Database

ServerMySQL

(mysqld)en

(mysql)

SQL


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Accessing DBMS by Web Applications

Web servers do not access the DBMS directly

A web-to-database middleware does

CGI program written in C, Pascal, PERL, etc.

ColdFusion, Active Server Page, PHP (Scripting Language)

We use PHP in our course

PHP has functions (application programming interface or

API) for manipulating a number of DBMS, such as Oracle,

, an y .


book.php

Web Server Machine

< >

PHP

Interpreter

MySQL

Database

Server

< >

Napoleon< /HTML>

W eb

Database

HTTP Requesthttp:/ /abc.com/book.php

INTERNET

Napoleon


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Example Form

ttp: sem . u.e u. ~ semuser mysq orm. tm

Customer ID Input Form


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The previous arrangement is a two-tier architecture, i.e., the web

browser (client) is responsible for presentation and the server machine

is responsible for business logic (processing) and data retrieval and

update.

What happen if the load of the web-server machine is very high or the

data base is very large (i.e., millions of records)?

e server mac nes can e arrange us ng ree- er en erver

Architecture

Web browser responsible for presentation (note: if javascript is used, the

browser also responsible for part of the processing)

Web Server machine responsible for business logic

Database Server machine responsible for data retrieval and update

You can arrange servers in n-tier architecture

Three-Tier Client Server Architecture

book.php

Web Server Machine (Wisdom)isem03

PHP

Interpreter

< >

Napoleon

Web

INTERNET

Server

INTERNET

MySQL

Database

Database

eques

http://abc.com/book.php

Napoleon

Server

(mysqld)

Database Server Machine (ISM02)


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Three-Tier Example

http://isem03.hkbu.edu.hk/~isemuser20/mysql/formthree.html

This is Three-tier demonstration


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Data Definition CommandsData Definition Commands

Creatin the Database Structure

Example:CREATE DATABASE db1020;


Creatin Table Structures

CREATE TABLE

);


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create table customer

(customer_id int not null unique,

customer_name varchar(20)not null,_ ,

primary key (customer_id));

create table orders

_

order_total float,

_ ,

order_date date,

_

Basic Data ManagementBasic Data Management

Data Entr

INSERT INTO VALUES (attribute 1

value, attribute 2 value, etc.);

insert into customer

values(1, ludwig chang, 12345678);

values(1, 200, 1, 2009-02-14);


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Makin a CorrectionUPDATE table name SET attribute = new_value

[, attribute = new_value ]

where conditions

update customer

se cus omer_p one =

where customer_id = 1;


DELETE FROMtable

WHERE conditions

or ers

WHERE order_id = 6;


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QueriesQueries

General Format of SELECT statement

SELECT [DISTINCT | ALL] {* | column_list}

FROM table name [alias] [, table_name [alias]] ....

[WHERE conditions ]

[GROUP BY column_list ]

[HAVING condition ]

ORDER BY column list _

select order_id, order_total from orderswhere customer id = 1_

+----------+-------------+

| order_id | order_total |

+----------+-------------+

| 1 | 200 |

| 2 | 500 |

+----------+-------------+

How to run MySQL statements in php ?

We just use a string to store the MySQL statement and

execute it using a php MySQL function statement


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MySQL statements

CREATE TABLE tonytable (first_name VARCHAR(30),second nameVARCHAR 30 a e INT_

INSERT INTO tonytable (first_name, second_name, age) VALUES (Tony,WONG,37);

*

UPDATE tonytable SET first_name = Samuel;

Using WHERE for checking conditions

Connecting to the MySQL sever mysql_connect ( )

Open a connection to a MySQL Server

mysql_connect ([string hostname [:port][:/path/to/socket] [, string username [, stringpasswor

Returns a pos t ve My L n dent er on success, or an

error message on failure.


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The following defaults are assumed for missing optional parameters:

= ' ' =,

the server process andpassword= empty password.

If a second call is made to mysql_connect( ) with the same arguments,

no new link will be established, but instead, the link identifier of the

already opened link will be returned.

The link to the server will be closed as soon as the execution of the

script ends, unless it's closed earlier by explicitly calling

mysql_close( ).

MySQL connect example

Ref : mysql01.php

htt ://isem03.hkbu.edu.hk/~isemuser20/m s l/m s l01. h


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_ _

with two major differences.

First, when connecting, the function would first try to find a

(persistent) link that's already open with the same host, username. ,

instead of opening a new connection.

Second, the connection to the SQL server will not be closed when

the execution of the script ends. Instead, the link will remain open

_

mysql_pconnect( )).

This type of links is therefore called 'persistent'.

- _ _

$db = db1020;

mysql_select_db($db) or die (Couldnt open $db);

Returns: true on success, false on error.

mysql_select_db( ) sets the current active database on the server that's associated

with the specified link identifier. If no link identifier is specified, the last

o ened link is assumed. If no link is o en the function will tr to establish a

link as ifmysql_connect( ) was called, and use it.

Every subsequent call to mysql_query( ) will be made on the active database.


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pen ng a connec on an e ec ng a a a ases

$user = isemuserXX;

$pass = your_password;

$db = db10XX;

$link = mysql_connect(localhost, $user, $pass);

If ! link

die (couldnt connect to MySQL);

print Successfully connected to sever

;

mysql_select_db( db) or

die (couldnt open $db : .mysql_error ( ));

print Sucessfully select database \$db\

;mysql_close($link);

?>

Ref : mysql02.php

http://isem03.hkbu.edu.hk/~isemuser20/mysql/mysql02.php

Other MySQL functions


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mysql_affected_rows ( ) Get number of affected rows inprevious MySQL operation

mysql_change_user ( ) Change logged in user of the activeconnec on

mysq _c ose ose y connec on

mysq _create_ reate a y ata ase

mysql_data_seek ( ) Move internal result pointer

mysq _ _name et resu t ata

mysq _db_query end a y query

mysql_drop_db ( ) Drop (delete) a MySQL database

mysql_errno ( ) Returns the numerical value of the errormessage from previous MySQL operation

mysql_error ( ) Returns the text of the error message fromprev ous y opera on


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mysq _ etc _array etc a resu t row as an assoc at vearray, a numeric array, or both.

mysql_fetch_assoc ( ) Fetch a result row as an associative

_ _and return as an object

mysql_fetch_lengths ( ) Get the length of each output in a

result

m s l fetch ob ect Fetch a result row as an ob ect_ _

mysql_fetch_row ( ) Get a result row as an enumerated array

mysql_field_flags ( ) Get the flags associated with thespecified field in a result

mysql_field_name ( ) Get the name of the specified field in aresult

mysql_field_len ( ) Returns the length of the specified field

mysql_field_seek ( ) Set result pointer to a specified fieldoffset


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mysql_field_table ( ) Get name of the table the specified fieldis in

mysql_field_type ( ) Get the type of the specified field in a

result

mysql_free_result ( ) Free result memory

mysql_insert_id ( ) Get the id generated from the previousINSERT operation

mysql_list_dbs ( ) List databases available on a MySQLserver

mysql_list_fields ( ) List MySQL result fields

m s l list tables ( ) List tables in a M S L database_ _

mysql_num_fields ( ) Get number of fields in result

m s l num rows Get number of rows in result_ _

mysql_query ( ) Send a MySQL query

m s l result Get result data_

mysql_tablename ( ) Get table name of field

Ch.8a Mysql Database

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