php pdo operation database, phppdo database_PHP tutorial

php pdo operates the database, phppdo database

POD extension is added in PHP5. This extension provides PHP built-in class PDO to access the database. Different databases use the same method name , solve the problem of inconsistent database connections.

Features of PDO:

Performance. PDO learned from the beginning about the successes and failures of scaling existing databases. Because PDO's code is brand new, we have the opportunity to redesign performance from the ground up to take advantage of PHP 5's latest features.
Ability. PDO is designed to provide common database functionality as a foundation while providing easy access to the unique features of an RDBMS.
Simple. PDO is designed to make working with databases easy for you. The API doesn't force its way into your code and makes it clear what each function call does.
Extensible at runtime. The PDO extension is modular, enabling you to load drivers for your database backend at runtime without having to recompile or reinstall the entire PHP program. For example, the PDO_OCI extension implements the oracle database API instead of the PDO extension. There are also drivers for MySQL, PostgreSQL, ODBC, and Firebird, with more in development.

PDO installation

You can check whether the PDO extension is installed through PHP’s phpinfo() function.

　1. Install PDO on Unix/Linux system

On Unix or Linux you need to add the following extension:

　extension=pdo.so

　2. Install pdo in Windows

PDO and all major drivers are shipped with PHP as shared extensions, to activate them simply edit the php.ini file and add the following extension:

　 extension=php_pdo.dll

In addition, there are various database extensions corresponding to the following:

<span class="pln"><span class="pun">　　　　;<span class="pln">extension<span class="pun">=<span class="pln">php_pdo_firebird<span class="pun">.<span class="pln">dll
　　　　<span class="pln"><span class="pun"><span class="pln"><span class="pun"><span class="pln"><span class="pun"><span class="pln"><span class="pun">;<span class="pln">extension<span class="pun">=<span class="pln">php_pdo_informix<span class="pun">.<span class="pln">dll
　　　　<span class="pun">;<span class="pln">extension<span class="pun">=<span class="pln">php_pdo_mssql<span class="pun">.<span class="pln">dll
　　　　<span class="pun">;<span class="pln">extension<span class="pun">=<span class="pln">php_pdo_mysql<span class="pun">.<span class="pln">dll
　　　　<span class="pun">;<span class="pln">extension<span class="pun">=<span class="pln">php_pdo_oci<span class="pun">.<span class="pln">dll
　　　　<span class="pun">;<span class="pln">extension<span class="pun">=<span class="pln">php_pdo_oci8<span class="pun">.<span class="pln">dll
　　　　<span class="pun">;<span class="pln">extension<span class="pun">=<span class="pln">php_pdo_odbc<span class="pun">.<span class="pln">dll
　　　　<span class="pun">;<span class="pln">extension<span class="pun">=<span class="pln">php_pdo_pgsql<span class="pun">.<span class="pln">dll
　　　　<span class="pun">;<span class="pln">extension<span class="pun">=<span class="pln">php_pdo_sqlite<span class="pun">.<span class="pln">dll</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>

Open php.ini and remove the semicolons in front of all the lines above.
After setting these configurations, we need to restart PHP or Web server.

Next we use mysql as an example to use pdo:

<?<span>php
$dbms='mysql';     //数据库类型
$host='localhost'; //数据库主机名
$dbName='test';    //使用的数据库
$user='root';      //数据库连接用户名
$pass='';          //对应的密码
$dsn="$dbms:host=$host;dbname=$dbName"<span>;


try<span> {
    $dbh = new PDO($dsn, $user, $pass); //初始化一个PDO对象
    echo "连接成功<br/>"<span>;
    /*你还可以进行一次搜索操作
    foreach ($dbh->query('SELECT * from FOO') as $row) {
        print_r($row); //你可以用 echo($GLOBAL); 来看到这些值
    }
    */
    $dbh = null<span>;
} catch (PDOException $e<span>) {
    die ("Error!: " . $e->getMessage() . "<br/>"<span>);
}
//默认这个不是长连接，如果需要数据库长连接，需要最后加一个参数：array(PDO::ATTR_PERSISTENT => true) 变成这样：
$db = new PDO($dsn, $user, $pass, array(PDO::ATTR_PERSISTENT => true<span>));

?></span></span></span></span></span></span></span></span>

　Let’s take a look at the detailed introduction of pdo:

1. Predefined constants:

2.PDO class:

• PDO::beginTransaction — Start a transaction
• PDO::commit — Commit a transaction
• PDO::__construct — Create a PDO instance that represents a database connection
• PDO::errorCode — Get the SQLSTATE
related to the last operation of the database handle
• PDO::errorInfo — Returns the error message of the last database operation
• PDO::exec — Execute a SQL statement and return the number of affected rows
• PDO::getAttribute — Retrieve attributes of a database connection
• PDO::getAvailableDrivers — Returns an array of available drivers
• PDO::inTransaction — Check if it is within a transaction
• PDO::lastInsertId — Returns the ID or sequence value of the last inserted row
• PDO::prepare — Prepares the SQL statement to be executed and returns a PDOStatement object
• PDO::query — Execute SQL statements and return PDOStatement objects, which can be understood as result sets
• PDO::quote — Add quotes to strings in SQL statements.
• PDO::rollBack — Roll back a transaction
• PDO::setAttribute — Set attributes
• PDOStatement class:
  
  • PDOStatement::bindColumn — Bind a column to a PHP variable
  • PDOStatement::bindParam — Bind a parameter to the specified variable name
  • PDOStatement::bindValue — Bind a value to a parameter
  • PDOStatement::closeCursor — Close the cursor so that the statement can be executed again.
  • PDOStatement::columnCount — Returns the number of columns in the result set
  • PDOStatement::debugDumpParams — Print a SQL preprocessing command
  • PDOStatement::errorCode — Get the SQLSTATE
  related to the last statement handle operation
  • PDOStatement::errorInfo — Get extended error information related to the last statement handle operation
  • PDOStatement::execute — execute a prepared statement
  • PDOStatement::fetch — Get the next row from the result set
  • PDOStatement::fetchAll — Returns an array containing all rows in the result set
  • PDOStatement::fetchColumn — Returns a single column from the next row in the result set.
  • PDOStatement::fetchObject — Gets the next line and returns it as an object.
  • PDOStatement::getAttribute — Retrieve a statement attribute
  • PDOStatement::getColumnMeta — Returns the metadata of a column in the result set
  • PDOStatement::nextRowset — Advance to the next rowset in a multi-rowset statement handle
  • PDOStatement::rowCount — Returns the number of rows affected by the previous SQL statement
  • PDOStatement::setAttribute — Set a statement attribute
  • PDOStatement::setFetchMode — Set the default fetch mode for statements.

<?php
if ($db->getAttribute(PDO::ATTR_DRIVER_NAME) == 'mysql') {
  echo "Running on mysql; doing something mysql specific here\n";
}
?>