Professional PHP Programming phần 4 ppt

You do not need a trained Database Administrator for administering a MySQL Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com... link_identifie which the request wi

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PHP Support for Database Connectivity

PHP supports API’s for accessing large numbers of databases like Oracle, Sybase, PostgreSQL, MySQL etc The PHP programs, to access the data from the database on the fly, can use these API's Open Database Connectivity (ODBC) is a standard Application Programming Interface (API) for accessing a database that has PHP support This can be used for writing generic database applications

By generic I mean that the same application code will work for all the Databases supporting the ODBC standard There will be a performance overhead with ODBC, if the database doesn’t support ODBC natively, and moreover ODBC being a generic standard supports only generic features If you want to use some specific feature of a database, then one should use the language API of that database

In this section we will cover PHP API’s for accessing MySQL databases You can look at the PHP documentation for APIs to access other databases Lets briefly cover the features of MySQL before we look into the PHP API’s

MySQL Database

MySQL is a small, compact, easy to use database server, ideal for small and medium sized applications It is a client/ server implementation that consists of a server daemon mysqld and many different client programs It is available on a variety of UNIX platforms, Windows NT and Windows 95/98 On UNIX platforms it uses threading, which makes it a high performance and highly scalable database server

The main features of a MySQL database server are described below

Programming Language API’s for Clients to Access the Database

MySQL database applications can be written in a set of languages like C, Perl, PHP etc

Large Tables

MySQL stores each table in the database as a separate file in the database directory The maximum size of a table can be between a minimum of 4GB and the Operating System limit on the maximum file size

Speed, Robustness and Ease of Use

MySQL is about three to four times faster than many other commercial databases MySQL is also very easy to manage You do not need a trained Database Administrator for administering a MySQL

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Cost Advantage

MySQL is an open source relational database It is distributed free of cost for UNIX and OS/2

platforms and for Microsoft platforms you need to get a license after a trial period of 30 days So with MySQL you get a cost advantage over other commercial relational databases

Database Features not present in MySQL

Though MySQL is a comprehensive database system, you should be aware of its limitations, which are detailed below Most of the web based database applications can be written without using these features But if your application needs these features to be present in the back end database, then you should consider using other commercial databases like SQL Server, Oracle etc., which support these features

Sub-selects

Sub-selects are not supported in MySQL

For Example, the following statement returns data about employees whose salaries exceed their department average:

SELECT deptno, ename, sal

Transactions

A Transaction is a logical unit of work that comprises one or more SQL statements executed by a single user A transaction ends when it is explicitly committed or rolled back by that user

For example in a Banking Application, when a bank customer transfers money from a savings account

to a checking account, the transaction might consist of three separate operations: decrease the savings account, increase the checking account, and record the transaction in the transaction journal When something prevents one of the statements in the transaction from executing (such as a hardware failure), the other statements of the transaction must be undone

Committing a transaction makes permanent the changes resulting from all SQL statements in the transaction

Rolling back a transaction retracts any of the changes resulting from the SQL statements in the transaction After a transaction is rolled back, the affected data is left unchanged as if the SQL statements in the transaction were never executed

Transactions are currently not supported in MySQL MySQL supports LOCK_TABLES and

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UNLOCK_TABLES commands to lock tables, which can be used by the thread to prevent interference

by other threads for concurrency issues MySQL does not support Row level locking of tables

LOCK_TABLES can lock multiple tables with the specified access i.e Read/ write Locks on a table get released when the thread holding the lock executes UNLOCK_TABLE command or when the thread holding the lock dies

Stored Procedures and Triggers

A stored procedure is a set of SQL commands that are compiled and are stored in the server Clients now can refer to the stored procedure, instead of reissuing the entire SQL commands You get performance benefit by using stored procedures, because the SQL statements are already parsed and compiled in the server, and less data needs to be sent to the server from the client

A trigger is a stored procedure that is invoked when a particular event occurs For example, a trigger can be set on a stock price table, the trigger gets fired after any UPDATE operation is done on that table The trigger can be set to send e-mails to interested people (taken from another table) if the stock

prices of any of the updated rows changes by 20%

However, MySQL does not have support for stored procedures and triggers

Foreign Keys

Different tables in a relational database can be related by common columns, and the rules that govern the relationship of the columns must be maintained Referential integrity rules guarantee that these relationships are preserved The column included in the definition of the referential integrity constraint that reference to a primary key of another table is called a foreign key

For example, a Dept column of the Employees table is a foreign key that refers to the Deptcolumn of the Departments Table Any insert done on the Employee Table with the wrong Deptcolumn value (i.e Department does not exist) will fail It means that there will be no employee entry

in the Employee Table, which will have a department that does not exist

MySQL does not support foreign keys However, the foreign key syntax in MySQL does exist, but only for compatibility with other database vendors, and it does not do anything

Views

A view is a tailored presentation of the data contained in one or more table (or other views) A view takes the output of a query and treats it as a table; therefore, a view can be thought of as a "stored query" or a "virtual table" No storage is allocated to View

For example, in employee table, you want all the users (who are not managers) to see only the name, and employee-id fields of the Table You can create a view on the table with the following SQL statement:

Create View Employee_View as SELECT name, employee-id FROM Employee

All the users (non-managers) can be given SELECT privilege on the Employee_View Now they will only be able to access name, and employee-id fields of the Employee table

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MySQL API Support in PHP

mysql_connect

Creates a connection to a MySQL Server

int mysql_connect(string [hostname [:port] [:/path_to_socket]], string

[username], string [password]);

The arguments for this function are given in the table below, and all of these are optional:

hostname The name of the host running the

database server There is no need to specify this if the database and the web server are running on the same machine

"localhost"

:port The port that the database server is

using for listening to requests Only needed if your setup uses a port different than the default for MySQL

":3306"

:/path_to_sock

et The Unix socket that the server is using

for listening to requests

":/tmp/mysql.sock"

username The name of the user allowed to connect

to the database server

The user that owns the web server process

password The password for the user; if missing it

is assumed empty

The first argument specifies the hostname (optionally port, else default port is assumed) or the UNIX domain socket, on which the MySQL server is listening for the client requests If the PHP program and the database server are running on the same machine, then they can communicate using the UNIX domain socket

Note that all the SQL (and other) commands sent to the MySQL server using this connection will be executed with the privileges of the username

The function returns a link identifier (a positive number which references the connection) on success,

or false on error This link identifier will be used in all the function calls, which send requests to the MySQL server

If another mysql_connect call is made with the same arguments, a new connection will not be created to the server The link identifier of the connection already open will be returned

The connection (between the PHP client program and the MySQL Server) will be closed when a mysql_close call is made, or when the PHP script exits

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mysql_pconnect

Creates a persistent connection to a MySQL Server

int mysql_pconnect(string [hostname [:port] [:/path_to_socket]], string [username], string [password]);

The function arguments and the return value are same as those for mysql_connect The difference between mysql_pconnect and mysql_connect is that the connection created with mysql_pconnect is not closed when the PHP program exits or a mysql_close call is made The PHP interpreter maintains the connection with the MySQL server When a mysql_pconnectcall is made, the PHP interpreter first finds out if there is an existing open connection with the same function arguments If it finds one then the link identifier of the existing connection is returned, instead of creating a new connection

The mysql_pconnect function should be used in PHP applications where, over a short period of time, a large number of connections will be made to the MySQL server using the same username and password mysql_pconnect saves the overhead of creating and closing a connection

Note that mysql_pconnect will work only if PHP is configured as a module in the web server

mysql_close

This will end the connection with the MySQL server and is optional

int mysql_close(int [link_identifier]);

The mysql_close function returns true on success, or false on error Note that mysql_closewill not close persistent links generated using mysql_pconnect

mysql_create_db

Creates a new database on the MySQL server

int mysql_create_db(string name, int [link_identifier]);

name The name of the database to be created

link_identifie

which the request will be sent to the The link identifier for the last connection

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The name parameter is required, though the link_identifier is optional The

mysql_create_db() function returns true on success, or false on failure

Alternatively mysql_query can be used to send the Create Database SQL command to the MySQL server to create a new database

mysql_drop_db

Drops (removes) a MySQL database

int mysql_drop_db(string database_name, int [link_identifier]);

name The name of the database to be deleted

link_identifie

which the request will be sent to the Database Server

The link identifier for the last connection opened

The name parameter is required, though the link_identifier is optional The function returns true on success, or false on failure

Alternatively mysql_query can be used to send the Drop Database SQL command to the MySQL server to delete a database

mysql_select_db

Selects a database as the active database

int mysql_select_db(string database_name, int [link_identifier]);

database_name The name of the database which is to

become the active database

link_identifie

The link identifier for the last connection opened If no connection is open, then the function tries

to open a new connection using

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All the SQL statements passed to the MySQL server will be made on the active database

mysql_query

Sends the SQL statement to the MySQL server for execution

int mysql_query(string query, int [link_identifier]);

query The SQL command to be sent to the

mysql_connect with

default parameters

The query parameter is required, though the link_identifier is optional The function returns a result identifier (positive integer) on success, or false on error The result identifier contains the result of the execution of the SQL statement on the MySQL server

In the case of Data Definition Language (DDL) SQL statements (CREATE, ALTER, DROP), the result identifier will indicate success or failure

In the case of Data Manipulation Language (DML) SQL statements DELETE, INSERT, UPDATE), the result identifier can be used to find out the number of affected rows by using

mysql_affected_rows() call, with the result identifier as an argument

With the DML statement SELECT, the result identifier will be an integer that corresponds to a pointer

to the result set This can be used to find the result of the SELECT statement with a mysql_result() call with the result identifier as an argument

For example, the following code creates a table named addressbook, which contains the addresses

of people Here the return value of mysql_query function is used to find whether the SQL command execution succeeded or failed

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$hostName = "www.harawat.com";

$databaseName = "php";

$tableName = "addressbook";

SQL statement for creating a table

$stmt = "CREATE TABLE %s(NAME CHAR(255), EMAIL CHAR(255),

CITY CHAR(255),

DESCRIPTION CHAR(255),

TELEPHONE CHAR(255),

ROWID INT PRIMARY KEY AUTO_INCREMENT)";

Function to print error messages

function printError($errorMesg)

{

printf("<BR> %s <BR>\n", $errorMesg);

}

Open a connection with the database server

// Connect to the Database

if (!($link=mysql_connect($hostName, $userName, $password))) {

printError(sprintf("error connecting to host %s, by user %s",

$hostName, $userName));

exit();

}

Create the database $databaseName

// Create the $databaseName database

if (!mysql_create_db($databaseName, $link)) {

printError(sprintf("Error in creating %s database", $databaseName));

printError(sprintf("error:%d %s", mysql_errno($link), mysql_error($link))); exit();

}

printf("<BR> Created Database %s <BR>\n", $databaseName);

Make the created database $databaseName as active database

// Make $databaseName the active database

if (!mysql_select_db($databaseName, $link)) {

printError(sprintf("Error in selecting %s database", $databaseName)); printError(sprintf("error:%d %s", mysql_errno($link), mysql_error($link))); exit();

}

Create the table address book

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// Create the table AddressBook

if (!mysql_query(sprintf($stmt,$tableName), $link)) { printError(sprintf("Error in executing %s stmt", $stmt));

printError(sprintf("error:%d %s", mysql_errno($link), mysql_error($link))); exit();

int mysql_db_query(string database, string query, int [link_identifier]);

database The name of the active database

query The SQL command to be sent to the

MySQL server

link_identifie

default parameters

The database and query parameters are required, though the link_identifier is optional The return values are same as in the case of mysql_db_query

For example, to SELECT all rows from the employee table in database1:

$stmt = "SELECT * from employee";

$result = mysql_db_query("database1", $stmt, $linkId);

Alternatively mysql_query can also be used by modifying the SQL statement

$stmt = "SELECT * from database1.employee";

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mysql_list_dbs

Lists databases available on the MySQL server

int mysql_list_dbs(int [link_identifier]);

link_identifie

default parameters

The link_identifier is optional The function returns a result identifier on success, else false

is returned on error The mysql_tablename() function should be used to traverse the result identifier to get the list of databases

mysql_list_tables

Lists all the tables in a MySQL database

int mysql_list_tables(string database, int [link_identifier]);

database Name of the Database, whose list of

tables will be returned

link_identifie

r

The reference for the connection on which the request will be sent to the Database Server

default parameters

The database parameter is required, though the link_identifier is optional The function returns a result identifier on success, else false is returned on error The mysql_tablename()function should be used to traverse the result identifier to get the list of databases

mysql_num_rows

Returns the number of rows in the result identifier (which contains the result of the executed SQL

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statement)

int mysql_num_rows(int result_identifier);

result_identifie

mysql_db_query, mysql_query, mysql_list_tables,

mysql_list_dbs

The result_identifier parameter is required, and this function is used when the query performed corresponded to a SELECT statement

mysql_tablename

Get the table/database name from the result identifier

string mysql_tablename(int result_identifier, int i);

result_identifie

mysql_list_tables, mysql_list_dbs

Open a connection with the Database Server

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if (!($link = mysql_connect($hostName, $userName, $password))) {

printf("<BR> error in connecting to the host %s <BR>\n", $hostName);

exit();

}

Get the list of Databases in the Server

// Get the list of Databases

if (!($listOfDbs = mysql_list_dbs($link))) {

printf("<BR> error in mysql_list_dbs, error %s <BR>\n", mysql_error($link)); exit();

}

printf("<b> Databases on %s </b> <br> <br>\n", $hostName);

// Get the list of Databases

$noOfDbs = 0;

Display the list of Databases

while ($noOfDbs < mysql_num_rows($listOfDbs)) {

printf(" %s <BR>\n", mysql_tablename($listOfDbs, $noOfDbs));

Retrieves the information about a table

int mysql_list_fields(string database_name, string table_name, int

[link_identifier]);

database_name The name of the database to which the

table belongs

table_name The name of the table about which to

list retrieve the information

link_identifie

to open a new

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connection using

default parameters

The database_name and table_name parameters are required, though the link_identifier

is optional The function returns a result identifier on success, or false on error

The result identifier can be used with mysql_field_flags(), mysql_field_len(), mysql_field_name(), mysql_field_type() calls to get the information about a table mysql_list_fields call is useful in the program, where you don't know beforehand the columns (or data types) of the table

mysql_num_fields

Gets the number of fields in a result set

int mysql_num_fields(int result_identifier);

result_identifie

mysql_list_dbsThe result_identifier parameter is required The function returns the number of fields in the

result_identifier

mysql_field_len

Gets the length of a field

int mysql_field_len(int result_identifier, int field_offset);

result_identifie

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mysql_field_name

Retrieves the name of a field in the database

string mysql_field_name(int result_identifier, int field_index);

result_identifie

mysql_list_dbs

field_index The index for the field in the result

identifier

The result_identifier and field_index parameters are required The function returns the

name of the field at offset field_index in the result_identifier

mysql_field_type

Returns the data type of a given field

string mysql_field_type(int result_identifier, int field_index);

result_identifie

Retrieves the flags for a given field

string mysql_field_flags(int result_identifier, int field_index);

result_identifie

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Retrieves the name of the table to which a specific field belongs

string mysql_field_table(int result_identifier, int field_index);

result_identifie

r

The result identifier returned by mysql_db_query, mysql_query, mysql_list_tables,

mysql_list_dbs

identifier

The result_identifier and field_index parameters are required The function returns the

name of the table, for the field at offset field_index in the result_identifier

mysql_affected_rows

Retrieves the number of rows affected by a SQL query

int mysql_affected_rows(int [link_identifier] );

link_identifier The reference for the connection on

which the SQL query was sent to the Database Server

The link_identifier parameter is optional The function returns the number of rows affected, in the previous SQL query

This call should be used to find out the number of rows inserted, updated or deleted by the previous SQL (INSERT, DELETE, REPLACE or UPDATE) query sent to the server If the last query was a DELETE without a WHERE clause (thus removing all records from a particular table), the function will return zero The number of rows returned by the SELECT SQL query should be found with

mysql_num_rows() function rather than with mysql_affected_rows()

mysql_insert_id

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executed INSERT SQL command on a table that contained an AUTO_INCREMENT column

int mysql_insert_id(int [link_identifier]);

which the INSERT SQL command was sent

mysql_fetch_row

Retrieves the next row from the result identifier, as an enumerated array

array mysql_fetch_row(int result_identifier);

result_identifie

mysql_list_dbs

The result_identifier parameter is required The function returns an array (corresponding to the current row ), or false if there are no more rows

mysql_fetch_row() internally increments the internal row pointer field of the

result_identifier So each subsequent call of mysql_fetch_row() will return the next row from the result

mysql_data_seek

Sets the internal row pointer of the result identifier

int mysql_data_seek(int result_identifier, int row_number);

result_identifie

mysql_fetch_row will return row_number row

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The function returns true on success, or false on error

mysql_fetch_field

Retrieves the column information from the result set

object mysql_fetch_field(int result_identifier, int [field_offset]);

result_identifie

r

The result_identifier parameter is required, though field_index is optional The function returns an object describing the field at offset field_offset, in the result_identifier If the optional argument field_offset is not specified, then the next field that was not retrieved with mysql_fetch_field is returned

The returned object has the following properties:

❑ name: column name

❑ table: name of the table the column belongs to

❑ max_length: maximum length of the column

❑ not_null: 1, if the column cannot be null

❑ primary_key; 1, if the column is a primary key

❑ unique_key: 1, if the column is a unique key

❑ multiple_key: 1, if the column is a non-unique key

❑ numeric: 1, if the column is numeric

❑ blob: 1, if the column is a BLOB

❑ type: the type of the column

❑ unsigned: 1, if the column is unsigned

❑ zerofill: 1, if the column is zero-filled

Example

SELECT employee.name, department.deptname Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com

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If mysql_fetch_field()is called on the result identifier containing the result of the above query, then the first call will return the description of employee.name field, and the second call will return the description of department.deptname field

mysql_field_seek

The function sets the fetch_field offset of the result_identifier to field_offset

int mysql_field_seek(int result_identifier, int field_offset);

result_identifie

mysql_list_dbs

field_offset The index for the field in the result

identifier The field_offset and result_identifier parameters are both required The next call to mysql_fetch_field() will return the object describing the field_offset, field of the result identifier

The function returns true on success, else false on failure

mysql_fetch_object

Returns an object that corresponds to the fetched row from the result identifier

object mysql_fetch_object(int result_identifier, int [result_type]);

result_identifie

r

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The function is similar to mysql_fetch_array, except that an object is returned, instead of an array Therefore only MYSQL_ASSOC or MYSQL_BOTH will make sense, because numbers cannot be names for object properties Therefore, if you need to access fields with the same name in different tables, you will need to alias them If you used the SELECT query:

SELECT tab1.id AS id1, tab2.id AS id2 ( )

Then you can access the results by using:

$result = mysql_query("SELECT ( )"); $row = mysql_fetch_object($result);

And then referring to $row->id1 and $row->id2 will return the corresponding result field

echo $row->deptname;

} mysql_free_result($result);

?>

In the above example, the columns of the rows are accessed by field names

mysql_fetch_array

Fetches the row as an associative array

array mysql_fetch_array(int result_identifier, int [result_type]);

result_identifie

mysql_list_dbs

result_type A constant indicating what type (or types)

of array to return

MYSQL_BOTH

The result_identifier parameter is required The second optional argument result_type

can have the following values

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❑ MYSQL_NUM: Will cause the returned array to contain numeric indices only (similar to mysql_fetch_row())

❑ MYSQL_ASSOC: Will cause the returned array to contain associative indices only

❑ MYSQL_BOTH: Will cause the returned array to contain both numeric and associative indices

If the second argument result_type is not specified, then MYSQL_BOTH is assumed as the value for the second argument

Each subsequent call of mysql_fetch_array() will return an array corresponding to the next row, or false if there are no more rows

This is an extended version of mysql_fetch_row(), which returns only a numerically indexed array By contrast mysql_fetch_array() returns the results also as an associative array using the field names as keys, this without incurring any performance penalties The limitation of the

associative array is that if there is duplication in the field names, the last one will take precedence and you will need to use the numerical index to extract the other fields with the same name, or use aliasing

of the result fields For example, if the SQL query was:

SELECT tab1.id, tab2.id ( ) FROM tab1,tab2 ( )

And you used:

$result = mysql_query("SELECT ( )");

$row = mysql_fetch_array($result);

Then, referring to $row["id"] will return the contents of tab2.id To access tab1.id, we can use $row[0] Alternatively, if your SQL query was:

SELECT tab1.id as id1, tab2.id as id2 ( )

Then you will be able to refer to $row["id1"] and $row["id2"] to access the corresponding field

Example

<?php

$stmt = "SELECT employee.name, department.deptname

FROM employee , department

WHERE emplyee.deptno = department.deptno";

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mysql_fetch_lengths

Retrieves the lengths of each field in the last fetched row

array mysql_fetch_lengths(int result_identifier);

The function returns an array that corresponds to the lengths of each field in the last row fetched by mysql_fetch_row(), or false on error

mysql_result

Get the data from the result identifier

mixed mysql_result(int result_identifier, int row, mixed [field]);

result_identifie

mysql_list_dbs

row The row from which to retrieve the data

field The field in the row from which to

retrieve the data

The next field in the row

The result_identifier and row parameters are required, though field is optional The function returns the contents of the row row and column field from the result_identifier The optional argument field can be column offset, column name or table.column_name If the field argument is not specified then the next field of the row is returned

mysql_free_result

The function frees the memory associated with the result identifier

int mysql_free_result(int result_identifier);

result_identifie

mysql_list_dbs

The result_identifier parameter is required The function is used only if you estimate that your script is using too much memory when running Calling this function on a result handler will free all associated data in memory

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mysql_errno

Returns the error number of the previous MySQL operation

int mysql_errno(int [link_identifier]);

which the previous request was sent to the Database Server

The link_identifier parameter is optional mysql_errno() should be used to get the error numbers generated by the MySQL server

See the MySQL mysqld_error.h file for the list of error numbers and their

descriptions

mysql_error

Returns the error message for the previous MySQL operation

string mysql_error(int [link_identifier]);

which the previous request was sent to the Database Server

The link_identifier parameter is optional mysql_error() should be used to get the error messages generated by the MySQL server Errors from the MySQL server do not cause halting of the script being processed

A Sample PHP-MySQL Application

Any PHP script accessing a MySQL database does the following:

1 Connect to the MySQL Database Server

2 Send the SQL query to the MySQL Database Server, and get the result

3 Use the set of API’s to get the data from the result that is returned in Step 2

4 Generate the HTML page, for displaying the contents

Let’s implement a sample web-based address book application The address book application allows users to create a new entry in the address book, delete an existing entry, modify an entry and search

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for entries The application uses MySQL for storing the addresses, and uses PHP for displaying the content in HTML format

The address book entries are stored in “addressbook” table The “addressbook” table can be created in the MySQL database by executing the following SQL command

CREATE addressbook ( NAME VARCHAR (255), CITY VARCHAR(255), DESCRIPTION VARCHAR(255), TELEPHONE VARCHAR(255), ROWID INT PRIMARY KEY AUTO_INCREMENT) ) ;

Each row in the addressbook table is uniquely identified by the ROWID field

Before looking at the code of the application, lets first look at a few screenshots to get a feel of the application

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This is the main page of the application From here, users can add new entries in the address book or search the address book, by clicking the appropriate button

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The search page, shown above, is returned when the user clicks on the Search Address Book button

on the main page Here the user specifies the search criteria The search functionality is quite simple,

it does not support wildcard characters like ‘*’, ‘?’ etc For the above search criteria, all the entries in the address book which contain the sub string ‘ha’ in the name attribute and sub string ‘ban’ in the

city attribute are returned

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This page contains the search results for the search criteria mentioned earlier From here the user can modify the attributes or delete the entries

For modifying the attributes the user, clicks on the Modify link corresponding to the entry This will

return the modify page, where the user can specify the new attributes for the entry For deleting an

entry the user clicks on the Delete link corresponding to the entry

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This page, allows the user to specify new attributes for an entry Having modified these attributes, the

user clicks on the Modify button

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This page is returned, after the user clicks on the Add a New Entry button on the main page User

enters the values for the attributes and clicks on the Add Entry button to create a new entry The Name and e-mail fields are mandatory fields

Now that we have looked at the screenshots of the application, and have a broad understanding of what it is meant to do, let’s look at the complete code of the application

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$hostName="www.harawat.com" ; // Machine on which MySQL Database is running

All the PHP scripts connect to the MySQL database as user ‘php’

$userName="php" ; // Database User Login

$password="php" ; // Database User Password

$databaseName = "php" ; // Database name

Name of the table, in which addressbook is stored

$tableName = "addressbook" ; // Name of the table

GenerateHTMLHeader() function is used to generate HTML header for all the pages of the application

// Generate the HTML header function GenerateHTMLHeader($message) {

printf("<HEAD> <TITLE> Address Book on the Web </TITLE> </HEAD>");

printf("<BODY TEXT=\"#000000\" BGCOLOR=\"#999999\" LINK=\"#0000EE\"

VLINK=\"#551A8B\" ALINK=\"#FF0000\">\n");

printf("<H1><FONT SIZE=+4>My Address Book</FONT></H1><BR><BR>");

printf("<TABLE CELLPADDING=4 CELLSPACING=0 BORDER=0 WIDTH=600>");

printf("<TR BGCOLOR=\"#DCDCDC\"><TD><FONT FACE=Arial><B>");

GenerateFrontPage() function generates the main page of the application

// Generates the main page function GenerateFrontPage() {

Generate a HTML form with action script as main.php

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Generate a button with value “Search Address Book”

printf("<INPUT TYPE=\"submit\" NAME=\"choice\" VALUE=\"Search Address Book\">"); printf("     ");

Generate a button with value “Add a New entry”

printf("<INPUT TYPE=\"submit\" NAME=\"choice\" VALUE=\"Add a New Entry\">"); printf("<BR>");

printf("<BR>");

Print the instructions on how to use the application:

printf("<UL>");

printf("<LI> Search entries in the Address Book by clicking on

<I>Search Address Book</I> button</LI>");

printf("<LI> Add entries to the Address Book by clicking on

<I>Add a new Entry</I> button </LI>");

printf("<LI> Modify an existing entry by clicking <I>Search Address Book</I> button first and then choosing the entry to Modify</LI>");

printf("<LI> Delete an existing entry by clicking <I>Search Address Book</I> button first and then choosing the entry to Delete</LI>");

printf("</UL>") ;

printf("</FORM>");

}

DisplayErrMsg() function displays the error message $message This function is used

throughout the code for displaying error messages

// Display error messages

function DisplayErrMsg( $message ) {

// Generate the HTML form for add/modify/search

function GenerateHTMLForm($formValues, $actionScript, $submitLabel) {

Generate a HTML form

printf("<FORM METHOD=post ACTION=\"%s\"><PRE>\n", $actionScript);

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Display the attributes of the entry in text boxes The text boxes will contain the existing values of the attributes (as in the case of modify), or will be empty (as in the case of search and add)

Generate a button with value $submitLabel

printf("<INPUT TYPE=submit VALUE=\"%s\">", $submitLabel );

Generate an HTML form with main.php as action script

printf("<BR><FORM ACTION=\"main.php\" METHOD=post>\n");

Create a submit button with value “Click”

printf("<INPUT TYPE=submit VALUE=\"Click\"> to return to Main Page\n");

}

main.php

The script main.php, generates the main page of the application This script also is executed, after the

user clicks on the Add a New Entry or Search Address Book button on the main page of the

application

<?php Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com

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require("common.php") ;

If the value of the form variable $choice is null, then generate the main page of the application:

// Check if the page is called for the first time

if (!$choice){

Generate the header of the main page:

GenerateHTMLHeader("Click below to access the Address Book");

Generate the main page

GenerateFrontPage();

If the value of the form variable $choice is “Search Address Book”, then generate an HTML form with which the user can specify the search criteria

} else if ($choice == "Search Address Book"){

GenerateHTMLHeader( "Search using the following criteria:" );

Generate an HTML form, containing a submit button with value “SEARCH” and action script set as search.php

GenerateHTMLForm( 0, "search.php", "SEARCH" );

}

If the value of the form variable $choice is “Add a New Entry”, then generate an HTML form with which the user can enter the attributes of the new entry

else if ($choice == "Add a New Entry"){

GenerateHTMLHeader( "Please fill in fields: (Name and E-mail mandatory)" );

Generate an HTML form, consisting of a submit button with value “ADD ENTRY” and action script set as add.php

GenerateHTMLForm(0, "add.php", "ADD ENTRY ") ;

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<?

//add.php

require("globals.php") ; require("common.php") ;

$addStmt holds a SQL statement template for inserting the row corresponding to the new entry in the database table

$addStmt = "Insert into $tableName(NAME, EMAIL, CITY, DESCRIPTION, TELEPHONE) values('%s', '%s', '%s', '%s', '%s')" ;

Verify that the user enters the mandatory attributes:

// Check if all the variables are entered

if (!$cn || !$mail ) { DisplayErrMsg(" Error: All the fields are mandatory") ; exit() ;

}

Open a persistent connection with the database server Remember that the variables $hostName,

$userName, $password are defined in globals.php file

if (!($link=mysql_pconnect($hostName, $userName, $password))) { DisplayErrMsg(sprintf("error connecting to host %s, by user %s", $hostName, $userName)) ;

exit() ; }

Select the database $databaseName The variable $databaseName is also defined in globals.php

// Select the Database

if (!mysql_select_db($databaseName, $link)) { DisplayErrMsg(sprintf("Error in selecting %s database", $databaseName)) ; DisplayErrMsg(sprintf("error:%d %s", mysql_errno($link), mysql_error($link)))

; exit() ; }

Send the SQL statement to the Database Server for execution

// Execute the Statement

if (!mysql_query(sprintf($addStmt,$cn, $mail, $locality, $description,

$telephonenumber), $link)) { DisplayErrMsg(sprintf("Error in executing %s stmt", $stmt)) ; DisplayErrMsg(sprintf("error:%d %s", mysql_errno($link), mysql_error($link))) Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com

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}

Generate the HTML header to display the status of the add operation

GenerateHTMLHeader("The entry was added succesfully");

Generate a footer, to take the user to the main page of the application

Verify if the search criteria is specified

// Check if at least one search criteria is entered

if (!$cn && !$mail && !$locality && !$description && !$telephonenumber) {

DisplayErrMsg(" Error: At least one search criteria should be present\n") ; exit() ;

}

Generate a SQL SELECT statement corresponding to the search criteria specified by the user:

// Generate the SQL command for doing a select from the Database

$searchStmt = "SELECT * from tableName where " ;

$searchStmt = "telephone '$telephonenumber' and " ;

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$stmt= substr($searchStmt, 0, strlen($searchStmt)-4) ;

Open a persistent connection with the Database Server

exit() ; }

Select the database $databaseName

; exit() ; }

Send the SQL command to the database server for execution

if (!($result =mysql_query($stmt, $link))) { DisplayErrMsg(sprintf("Error in executing %s stmt", $stmt)) ; DisplayErrMsg(sprintf("error:%d %s", mysql_errno($link), mysql_error($link)))

; exit() ; }

Display the results of the SELECT query

// Display the results of the search

Each row in the result of the SQL query is displayed in a separate row of the table

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while (($row = mysql_fetch_object($result))){

The last column of the row contains links for deleting the entry

(HREF=\"delete.php?rowid=%s\") or modifying (HREF=\"modify.php?rowid=%s\") the attributes of the entry Each entry is uniquely identified by the ROWID attribute Notice that

modify.php and delete.php are called with rowid variable containing the ROWID attribute of the entry

<?

// modify.php

require("globals.php") ;

SQL statement to get the current values of the entry:

$selectStmt = "SELECT * FROM $tableName WHERE ROWID=$rowid" ;

Open a persistent connection with the Database Server:

if (!($link=mysql_pconnect($hostName, $userName, $password))) {

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DisplayErrMsg(sprintf("error connecting to host %s, by user %s", $hostName, $userName)) ;

exit() ; }

Select the database $databaseName:

; exit() ; }

Send the SQL statement to the database server for execution:

if (!($result= mysql_query($selectStmt, $link))) { DisplayErrMsg(sprintf("Error in executing %s stmt", $selectStmt)) ; DisplayErrMsg(sprintf("error:%d %s", mysql_errno($link), mysql_error($link)))

; exit() ; }

Generate the HTML header with message “Please modify fields”:

GenerateHTMLHeader( "Please modify fields") ;

Fetch the row from the $result variable:

GenerateHTMLForm( $resultEntry, "update.php?rowid=$rowid", "MODIFY" );

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mysql_free_result($result) ;

?>

update.php

The script update.php, updates the attributes of an entry in the database table It gets called, when

the user, after entering the new attributes of the entry, clicks on the MODIFY button on the Modify

page The script is called with form variables $cn, $mail, $locality, $description and

$telephonenumber containing the new attributes of the entry The form variable $rowid contains the value of ROWID attribute of the entry, and it uniquely identifies the entry

<?

// update.php

require("globals.php") ;

SQL statement for updating the attributes of the entry:

$updateStmt = "Update $tableName set NAME='$cn', EMAIL='$mail',

CITY='$locality', DESCRIPTION='$description', TELEPHONE='$telephonenumber' WHERE ROWID=$rowid" ;

Open a persistent connection with the Database Server:

if (!($link=mysql_pconnect($hostName, $userName, $password))) {

DisplayErrMsg(sprintf("error connecting to host %s, by user %s",

$hostName, $userName)) ;

exit() ;

}

Send the SQL statement to the database server for execution:

if (!mysql_query($updateStmt, $link)) {

DisplayErrMsg(sprintf("Error in executing %s stmt", $updateStmt)) ;

DisplayErrMsg(sprintf("error:%d %s", mysql_errno($link), mysql_error($link)))

;

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exit() ; }

Display the operation successful message

GenerateHTMLHeader("The entry was modified succesfully");

Display the footer, to take the user to the main page of the application

<?

// delete.php

require("common.php") ; require("globals.php") ;

SQL statement for deleting the entry from the database table:

$deleteStmt = "DELETE from $tableName where ROWID=$rowid" ;

Open a persistent connection with the database server:

exit() ; }

if (!mysql_select_db($databaseName, $link)) { DisplayErrMsg(sprintf("Error in selecting %s database", $databaseName)) ; DisplayErrMsg(sprintf("error:%d %s", mysql_errno($link), mysql_error($link))); exit() ;

}

Send the SQL statement to the database server for execution

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if (!mysql_query($deleteStmt, $link)) {

DisplayErrMsg(sprintf("Error in executing %s stmt", $deleteStmt)) ;

DisplayErrMsg(sprintf("error:%d %s", mysql_errno($link), mysql_error($link))); exit() ;

}

Generate the HTML header to display the status of delete operation

// Add the code to show the success

GenerateHTMLHeader("The entry was deleted succesfully");

Generate a footer, to take the user to the main page of the application

Here is what we covered in this chapter

❑ A basic introduction to databases;

❑ Basic SQL commands, including data definition and data manipulation statements;

❑ Features of the MySQL database;

❑ PHP API’s for accessing MySQL database;

❑ A sample database web application

Tiêu đề	Professional PHP Programming phần 4 ppt
Trường học	University
Chuyên ngành	Computer Science
Thể loại	Slide presentation

Định dạng
Số trang	86
Dung lượng	1,93 MB