PHP newbie (11) Database link

Database Connection 10. The biggest feature of PHP is its powerful ability to operate databases. PHP provides support for a variety of databases. With PHP, you can easily connect to the database, request data and display it on your web site, or even modify data in the database. In this section we mainly use the most popular MySQL with PHP on the Internet "> <LINKhref =" http://www.ph

Database link

 

10. The biggest characteristic of PHP is its powerful ability to operate databases. PHP provides support for multiple databases.

With PHP, you can easily connect to the database, request data and display it on your web site, or even modify data in the database. In this section, we will take the MySQL database that is most used with PHP on the Internet as an example, this section describes the related MySQL database operation functions and basic database operations.

In the MySQL database, there are two functions used to connect to the database:
Integer mysql_connect (string host, string user, string password );
Integer mysql_pconnect (string host, string user, string password );
Both the mysql_connect function and mysql_pconnect function connect to the MySQL database on the specified host. if the database is on a different port, you can add a colon and port number to the host name. Function parameters can also be left blank by default. If no parameter is set, the default host name is "localhost", the user name is the database administrator, the default value is "root", and the password is blank. After the connection to the database is successful, both functions can return a connection number. if the connection fails, a false value is returned. Let's take a look at the following statements:
$ Db = mysql_connect ("localhost", "user", "password ");
Mysql_select_db ("mydb", $ db );
?>
Note:
$ Db = mysql_connect ("localhost", "user", "password"); the connection parameters of mysql, including the host name, user name, and password, are used as the parameters of mysql_connect, at the same time, the returned value is $ db. in this way, in the following statement, we can use the variable $ db as the connection number to connect to the mysql database.
Mysql_select_db ("mydb", $ db); link the PHP program to the mydb database so that the link between the program and the database is complete.

10.1 A simple database message book

After connecting the database, we can perform a series of operations on the database. The following is a simple database message book program (guestbook. php3 ):

I assume that the MySQL database on your machine and the Phpmyadmin_2. 0.5 tool for managing the MYSQL database have been installed and can work properly.

The first thing we need to do is create a message database, which is assumed to be named mydb.

1. start the browser and open the management WEB interface of Phpmyadmin_2. 0.5.

2. enter the database name mydb in the "Create new database" text box, and press the create button.

Next, we will create a data table in the left-message database, assuming the name is guestbook.

The command for creating a data table is as follows:

Create table guestbook (id int not null AUTO_INCREMENT, name CHAR (250), email CHAR (250), job CHAR (250), comments BLOB, primary key (ID ));

Finally, copy the following message book program to the writeable directory of your machine and save it as the guestbook. php3 file. That's simple. you already have your own guestbook.

10.2 guestbook program (guestbook. php3 ):

/* $ Host: your MySQL-host, usually 'localhost '*/
/* $ User: your MYSQL-username */
/* $ Password: your MySQL-password */
/* $ Database: your MySQL-database */
/* $ Table: your MySQL-table */
/* $ Page_title: the title of your guestbook-pages */
/* $ Admin_mail: email-address of the administrator to send the new entries */
/* $ Admin_name: the name of the administrator */
/* $ Html_mail: say yes if your mail-agent can handle HTML-mail, else say no */

$ Host = "localhost ";
$ User = "";
$ Password = "";
$ Database = "mydb ";
$ Table = "guestbook ";
$ Page_title = "pert guestbook ";
$ Admin_mail = "pert@21cn.com ";
$ Admin_name = "Webmaster ";
$ Html_mail = "no ";

?>


<? Php echo $ page_title;?>

/* Connect to the database */
Mysql_pconnect ("$ host", "$ user", "$ password") or die ("Can't connect to the SQL-server ");
Mysql_select_db ("$ database ");

/* Action = view: retrieve data from the database and show it to the user */
If ($ action = "view "){

/* Function for showing the data */
Function search_it ($ name ){

/* Some vars */
Global $ offset, $ total, $ lpp, $ dir;
Global $ table, $ html_mail, $ admin_name, $ admin_mail;

/* Select the data to get out of the database */
$ Query = "SELECT name, email, job, comments FROM $ table ";
$ Result = mysql_query ($ query );
$ Total = mysql_numrows ($ result );

Print"

Add message

";

If ($ total = 0 ){
Print"

No one left a message at the moment

";}

Elseif ($ total> 0 ){

/* Default */
$ Counter = 0;
If ($ dir = "") $ dir = "Next ";
$ Lpp = 5;
If ($ offset = 0) $ offset = 0;

If ($ dir = "Next "){

If ($ total> $ lpp ){

$ Counter = $ offset;
$ Offset = $ lpp;
$ Num = $ offset;

If ($ num> $ total ){
$ Num = $ total ;}}

Else {
$ Num = $ total ;}}

Elseif ($ dir = "Previous "){

If ($ total> $ lpp ){
$ Offset-= $ lpp;

If ($ offset <0 ){
$ Offset = 0 ;}

$ Counter = $ offset-$ lpp;

If ($ counter <0)
$ Counter = 0;
$ Num = $ counter $ lpp ;}

Else {
$ Num = $ total ;}}

While ($ counter <$ num ){
$ J = 0;
$ J = $ counter 1;

/* Now really grab the data */
$ I1 = mysql_result ($ result, $ counter, "name ");
$ I2 = mysql_result ($ result, $ counter, "email ");
$ I3 = mysql_result ($ result, $ counter, "job ");
$ I4 = mysql_result ($ result, $ counter, "comments ");

$ I4 = stripslashes ("$ i4 ");

/* Print it in a nice layout */
Print"

N ";
Print"

N "; Print "n "; Print" Name:$ I1n "; Print" Email:$ I2n "; Print" Job:$ I3n "; Print" Comment:N "; Print" $ I4n "; Print"

N ";
Print" N ";
$ Counter;
}
}
Mysql_close ();
}

/* Execute the function */
Search_it ($ name );

/* See if we need to put on the NEXT or PREVIOUS buttons */
If ($ total> $ lpp ){
Echo ("");
}
}

/* Action = add: show a form where the user can enter data to add to the database */
Elseif ($ action = "add") {?>

Enter a message

}

/* Action = send: add the data from the user into the database */
Elseif ($ action = "send "){

/* Check if a HTML-mail shocould be send or a plain/text mail */
If ($ html_mail = "yes "){
Mail ("$ admin_name <$ admin_mail>", "PHP3 Guestbook Addition ","

$ Name ($ email) schreef het volgende bericht in het gastenboek:

$ Comments
Your message:	$ Name
Your name:	$ Email
Your email:	$ Job
Your work:

"," From: $ name <$ email> nReply-To: $ name <$ email> nContent-type: text/htmlnX-Mailer: PHP/". phpversion ());
}

/* MySQL really hates it when you try to put things with 'or "characters into a database, so strip these ...*/
$ Comments = addslashes ("$ comments ");
$ Query = "insert into guestbook VALUES ('', '$ name',' $ email ',' $ job', '$ comments ')";
$ Result = MYSQL_QUERY ($ query );

?>

Thanks, , Your message.

View messages

 

}

/* If there's no action given, then we must show the main page */
Else {

/* Get the number of entries written into the guestbook */
$ Query = "SELECT name from guestbook ";
$ Result = MYSQL_QUERY ($ query );
$ Number = MYSQL_NUMROWS ($ result );

If ($ number = ""){
$ Entry = "no one has left a message ";}

Elseif ($ number = "1 "){
$ Entry = "currently one member ";}

Else {
$ Entry = "current number of people leaving a message $ number ";}

Echo"

";
Echo"

$ Entry
";
Echo "please leave a message ";

If ($ number> ""){
Echo "Watch message ";}
Echo"

";
}
?>

Copyright: boundless sky