LXI. MySQL Functions
These functions allow you to access MySQL database servers.
More information about MySQL can be found at http://www.mysql.com/.
Documentation for MySQL can be found at http://www.mysql.com/documentation/.
In order to have these functions available, you must compile PHP with
MySQL support
By using the --with-mysql configuration
option you enable PHP to access MySQL databases. If you use this option
without specifying the path to MySQL, PHP will use the built-in MySQL
client libraries. With PHP4 MySQL support is always eanbled; if you don't
specify the configure option, the bundled libraries are used. Users who
run other applications that use MySQL (for example, running PHP 3 and PHP
4 as concurrent apache modules, or auth-mysql) should always specify the
path to MySQL: --with-mysql=/path/to/mysql. This will force
PHP to use the client libraries installed by MySQL, avoiding any
conflicts.
The behaviour of the MySQL functions is affected by settings in the
global configuration file php.ini.
Table 1. MySQL Configuration Options
| Name | Default | Changeable |
|---|
| mysql.allow_persistent | "On" | PHP_INI_SYSTEM |
| mysql.max_persistent | "-1" | PHP_INI_SYSTEM |
| mysql.max_links | "-1" | PHP_INI_SYSTEM |
| mysql.default_port | NULL | PHP_INI_ALL |
| mysql.default_socket | NULL | PHP_INI_ALL |
| mysql.default_host | NULL | PHP_INI_ALL |
| mysql.default_user | NULL | PHP_INI_ALL |
| mysql.default_password | NULL | PHP_INI_ALL |
For further details and definition of the PHP_INI_* constants see
ini_set().
Here is a short explanation of the configuration directives.
There are two resource types used in the MySQL module. The first one
is the link identifier for a database connection, the second a resource
which helds the result of a query.
The function mysql_fetch_array() uses a constant for
the different types of result arrays. The following constants are
defined:
Table 2. MySQL fetch constants
| constant | meaning |
|---|
| MYSQL_ASSOC |
Columns are returned into the array having the fieldname as the array
index.
|
| MYSQL_BOTH |
Columns are returned into the array having both a numerical index
and the fieldname as the array index.
|
| MYSQL_NUM |
Columns are returned into the array having a numerical index to the
fields. This index starts with 0, the first field in the result.
|
This simple example shows how to connect, execute a query, print
resulting rows and disconnect from a MySQL database.
Example 1. MySQL extension overview example <?php
/* Connecting, selecting database */
$link = mysql_connect("mysql_host", "mysql_login", "mysql_password")
or die("Could not connect");
print "Connected successfully";
mysql_select_db("my_database") or die("Could not select database");
/* Performing SQL query */
$query = "SELECT * FROM my_table";
$result = mysql_query($query) or die("Query failed");
/* Printing results in HTML */
print "<table>\n";
while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) {
print "\t<tr>\n";
foreach ($line as $col_value) {
print "\t\t<td>$col_value</td>\n";
}
print "\t</tr>\n";
}
print "</table>\n";
/* Free resultset */
mysql_free_result($result);
/* Closing connection */
mysql_close($link);
?> |
|
