PDOStatement::setFetchMode

(PHP 5 >= 5.1.0, PECL pdo >= 0.2.0)

PDOStatement::setFetchMode — 为语句设置默认的获取模式。

说明

bool PDOStatement::setFetchMode ( int $mode )

bool PDOStatement::setFetchMode ( int $PDO::FETCH_COLUMN , int $colno )

bool PDOStatement::setFetchMode ( int $PDO::FETCH_CLASS , string $classname , array $ctorargs )

bool PDOStatement::setFetchMode ( int $PDO::FETCH_INTO , object $object )

参数

mode: 获取模式必须是 PDO::FETCH_* 系列常量中的一个。
colno: 列号。
classname: 类名。
ctorargs: 构造函数参数。
object: 对象。

返回值

成功时返回 TRUE ，或者在失败时返回 FALSE 。

范例

Example #1 设置获取模式

The following example demonstrates how PDOStatement::setFetchMode() changes the default fetch mode for a PDOStatement object.下面的例子示范如何用 PDOStatement::setFetchMode() 来为一个 PDOStatement 对象更改默认的获取模式。

  <?php
$sql  =  'SELECT name, colour, calories FROM fruit' ;
try {
   $stmt  =  $dbh -> query ( $sql );
   $result  =  $stmt -> setFetchMode ( PDO :: FETCH_NUM );
  while ( $row  =  $stmt -> fetch ()) {
    print  $row [ 0 ] .  "\t"  .  $row [ 1 ] .  "\t"  .  $row [ 2 ] .  "\n" ;
  }
}
catch ( PDOException $e ) {
  print  $e -> getMessage ();
}
 ?>

以上例程会输出：

apple   red     150
banana  yellow  250
orange  orange  300
kiwi    brown   75
lemon   yellow  25
pear    green   150
watermelon      pink    90

用户评论:

[#1] Dormilich at netscape dot net [2010-07-13 02:16:22]

if you want to fetch your result into a class (by using PDO::FETCH_CLASS) and want the constructor to be executed *before* PDO assings the object properties, you need to use the PDO::FETCH_PROPS_LATE constant:

<?php $stmt = $pdo->prepare("your query"); $stmt->setFetchMode(PDO::FETCH_CLASS|PDO::FETCH_PROPS_LATE, "className", $constructorArguments); # pass parameters, if required by the query $stmt->execute($parameters); foreach ($stmt as $row) { // do something with (each of) your object } ?>

[#2] stein_AT_rhrk.uni-kl.de [2007-11-19 16:04:24]

Some note on PDO :: FETCH_CLASS | PDO :: FETCH_CLASSTYPE

It took me some time, to realize, that you can not use this fetch-mode in $stm->setFetchMode(), when you want to retrieve objects from the database whereas the type is defined by the first column in the resultset.
You have to define this mode directly in the $stm->fetch() method.

To make it clearer:

$stm = $pdo->query("SELECT * FROM `foo`);
$stm->setFetchMode(FETCH_CLASS | PDO :: FETCH_CLASSTYPE);

$object = $stm->fetch();

Will not return the expected object, whereas

$stm = $pdo->query("SELECT * FROM `foo`");

$object = $stm->fetch(FETCH_CLASS | PDO :: FETCH_CLASSTYPE);

will give you the object of the class, defined in the first column of `foo`.

[#3] matt at kynx dot org [2006-02-18 03:13:30]

To fetch the rows into an existing instance of a class, use PDO::FETCH_INTO and pass the object as the second parameter.

The class _must_ have the column names declared as public members, or the script will die. But overloading with __set() and __get() lets it handle any column your query throws at it.

Set the fetch mode right after you call prepare(). It appears you _must_ use execute() - fetch() won't work. A small example, adapted from ext/pdo/tests/pdo_025.phpt:

<?php class Test { protected $cols; function __set($name, $value) { $this->cols[$name] = $value; } function __get($name) { return $this->cols[$name]; } } $obj = new Test(); $db = PDOTest::factory(); $stmt = $db->prepare("select * from test"); $stmt->setFetchMode(PDO::FETCH_INTO, $obj); $stmt->execute(); foreach ($stmt as $a) { print_r($a); } print_r($obj); // contains the same values as the last iteration above ?>

[#4] Dariusz Kielar [2006-02-12 22:55:43]

PDO::FETCH_CLASS may be used only with this method and it takes up to three parameters then:
- int mode
- string className
- array constructorArgs (optional)

<?php $stmt = $pdo -> query('your query'); $stmt -> setFetchMode(PDO::FETCH_CLASS, 'yourClass', array(0 => false)); while($row = $stmt -> fetch()) { // $row is an object of "yourClass" class } $stmt -> closeCursor(); ?>

Note also that the constructor is called AFTER the data is set on the object.