How PHP operates the MySQL database

Use the mysql_connect () function to connect to the MySQL server

To operate the MySQL database, you must first establish a connection to the MySQL server. The following statements connect to the MySQL server:

mysql_connect (' hostname ', ' username ', ' password ');

The return value of the function represents the database connection. If the connection succeeds, the function returns a resource to prepare for executing the SQL command later.

The instance code is as follows:

<?php $link = mysql_connect ("localhost", "root", "root") or Die ("Cannot connect to the database server! May be

The database server is not started or the user name password is incorrect!   ". Mysql_error ()); Connect to MySQL server

if ($link) {

echo "Data connection succeeded!";

}

?>

Operation Result:

Use the mysql_select_db () function to select a database file

After connecting to the MySQL database server, next use the mysql_select_db () function to select the database.

The syntax format is as follows:

mysql_select_db (String database name [, Resource Link_identifier])

Or

Mysql_qurey ("Use database name" [. Resource Link_identifier]);

The instance code is as follows:

<?php
$link = mysql_connect ("localhost", "root", "root") or Die ("Cannot connect to the database server! The database server may not be started, or the user name password is incorrect!   ". Mysql_error ()); Connect to MySQL server
$db _selected=mysql_select_db ("Db_database18", $link);
$db _selected=mysql_query ("Use Db_database18", $link);
if ($db _selected) {
echo "Database selection succeeded!";
}
?>

Operation Result:

How PHP operates the MySQL database