Detailed explanation of PHP5 PDO connection to database_PHP tutorial

This article introduces PHP5 PDO to connect to the database
1. Introduction to PDO
PDO (PHP Data Object) is something added in PHP 5. It is a major new feature added in PHP 5, because in PHP 5 In the past, php4/php3 had a bunch of database extensions to connect and process each database, such as php_mysql.dll, php_pgsql.dll, php_mssql.dll, php_sqlite.dll, etc.
PHP6 will also use PDO to connect by default, and the mysql extension will be used as an auxiliary

2. PDO configuration
In PHP.ini, remove "extension=php_pdo. dll". If you want to connect to the database, you also need to remove the ";" sign in front of the database extension related to PDO, and then restart the Apache server.
extension=php_pdo.dll
extension=php_pdo_mysql.dll
extension=php_pdo_pgsql.dll
extension=php_pdo_sqlite.dll
extension=php_pdo_mssql.dll
extension=php_pdo_odbc.dll
extension=php_pdo_firebird.dll
......

3. PDO connects to mysql database
new PDO("mysql:host=localhost;dbname=db_demo" ,"root","");
The default is not a long connection. If you want to use a long connection to the database, you need to add the following parameters at the end:
new PDO("mysql:host=localhost;dbname=db_demo"," root","","array(PDO::ATTR_PERSISTENT => true) ");

4. Common PDO methods and their applications
PDO::query() Mainly used for operations that return recorded results, especially SELECT operations
PDO::exec() Mainly used for operations that do not return a result set, such as INSERT, UPDATE and other operations
PDO::lastInsertId() returns In the last insertion operation, the primary key column type is the last auto-incremented ID
PDOStatement::fetch() is used to get a record
PDOStatement::fetchAll() is used to get all the record sets into one

5. PDO operates MYSQL database instance
$pdo = new PDO("mysql:host=localhost;dbname=db_demo","root", "");
if($pdo -> exec("insert into db_demo(name,content) values(title,content)")){
echo "Insertion successful!";
echo $ pdo -> lastinsertid();
}
?>
$pdo = new PDO("mysql:host=localhost;dbname=db_demo","root", "");
$rs = $pdo -> query("select * from test");
while($row = $rs -> fetch()){
print_r($row );
}
?>

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