PHP connection MySQL Database Several methods introduction of MySQL, Mysqli, PDO Way

I. Characteristics and comparison

The MySQL extension of PHP is an early extension of design and development that allows PHP applications to interact with MySQL databases. The MySQL extension provides a process-oriented interface and is designed for MySQL4.1.3 or earlier versions. As a result, this extension can interact with the MySQL4.1.3 or updated database server, but does not support some of the features provided by the late MySQL server. Because it is too old and unsafe, it has been completely replaced by the later mysqli.
PHP's mysqli extensions, which we sometimes call MySQL enhanced extensions, can be used to use new advanced features in MySQL4.1.3 or newer versions. Its features are: Object-oriented interface, prepared statement support, multiple statement execution support, transaction support, enhanced debugging capability, embedded service support, and preprocessing method completely solve the problem of SQL injection. But it also has the drawback, is only supports the MySQL database. If you do not operate other databases, this is certainly the best choice.
PDO is the abbreviation for PHP Data Objects, which is a database abstraction layer specification in PHP applications. PDO provides a unified API interface that allows your PHP application to not care about the type of database server system you want to connect to. That is, if you use the PDO API, you can seamlessly switch database servers whenever you need them, such as from Oracle to MySQL, and you'll just need to modify a few PHP code. It features similar interfaces as JDBC, ODBC, DBI, and so on. In the same way, it solves the problem of SQL injection and has good security. However, he also has shortcomings, some multiple statement execution query does not support (but this situation is very small).

Guanven also makes a list comparison between the three:

PHP's mysqli extension	PDO (using PDO mysql driver and MySQL native driver)	PHP's MySQL extensions
Introduction of PHP Version	5.0	5.0	Before 3.0
Whether the php5.x contains	Is	Is	Is
MySQL Development status	Active	Active in the PHP5.3	Maintenance only
Recommended usage in new MySQL project	Recommendations-Preferred	Suggestions	Not recommended
Character set support for APIs	Is	Is	Whether
Support for service-side prepare statements	Is	Is	Whether
Support for client Prepare statements	Whether	Is	Whether
Stored Procedure Support Scenarios	Is	Is	Whether
Multi-statement execution support scenarios	Is	Most	Whether
Whether to support all MySQL4.1 or above features	Is	Most	Whether

From the official point of view, the first recommendation Msqli, followed by PDO. and "Folk" gives a lot of results are inclined to use PDO, because it does not have the advantages of cross-Library, more read and write faster characteristics.
51cto gives the relevant test results (somewhat old, 2011 test results).
Second, the module installs and calls
Take Ubuntu and its derivative version as an example, through sudo apt-get install mysqlnd can increase the PHP PDO and mysqli support (source installation can choose Phpize Program to dynamically expand). You can open the view through the Phpinfo page, where under MYSQLND, you can see the following:

API Extensions Mysql,mysqli,pdo_mysql

Mysqli and PDO connection methods

Pdo
$pdo = new PDO ("Mysql:host=localhost;dbname=database", ' username ', ' password ');
MYSQLI, process-oriented approach
$mysqli = Mysqli_connect (' localhost ', ' username ', ' password ', ' database ');
Mysqli, Object oriented
$mysqli = new mysqli (' localhost ', ' username ', ' password ', ' database ');

mysqli example of a query through a configuration file:

Configuration file

yang@crunchbang:/var/www/t$ Cat config.ini.php

Query code

yang@crunchbang:/var/www/t$ Cat mysqlquery.php
-->Query ("Set names $charName");
3, processing results
$res = $MYSQLIOBJ->query ($sql);
Var_dump ($res);
FETCH_ASSOC \fetch_array \fetch_object
while ($row = $res->fetch_row ()) {
Print_r ($row);
foreach ($row as $val) {
Echo '--'. $val;
}
Echo '                '
}
4. Close Resources
$res->free ();
$MYSQLIOBJ->close ();
?>

Queries made in PDO mode

SetAttribute (Pdo::attr_errmode, pdo::errmode_exception);
$r = $dbh->query (' SELECT * from user ');
Var_dump ($R);
foreach ($r as $v) {
Var_dump ($v);
}
?>

Summary:
programs like Discuz, PHPCMS, akcms generally provide two ways to connect mysqli or pdo-mysql (provided your deployment environment is supported), depending on your own situation when using classes in the above PHP program.