PDOStatement::fetch

(PHP 5 >= 5.1.0, PHP 7, PHP 8, PECL pdo >= 0.1.0)

PDOStatement::fetch — 結果セットから次の行を取得する

説明

public PDOStatement::fetch(int $mode = PDO::FETCH_DEFAULT, int $cursorOrientation = PDO::FETCH_ORI_NEXT, int $cursorOffset = 0): mixed

PDOStatementオブジェクトに関連付けられた結果セットから1行取得します。 mode パラメータは、PDO がその行をどの様に返すかを決定します。

パラメータ

mode

次のレコードを呼び出し元に返す方法を制御します。この値は、PDO::FETCH_* 定数のどれかで、デフォルトは PDO::ATTR_DEFAULT_FETCH_MODE の値 (そのデフォルトは PDO::FETCH_BOTH) です。

PDO::FETCH_ASSOC: は、結果セットに返された際のカラム名で添字を付けた配列を返します。
PDO::FETCH_BOTH (デフォルト): 結果セットに返された際のカラム名と 0 で始まるカラム番号で添字を付けた配列を返します。
PDO::FETCH_BOUND: true を返し、結果セットのカラムの値を PDOStatement::bindColumn() メソッドでバインドされた PHP 変数に代入します。
PDO::FETCH_CLASS: 結果セットのカラムがクラス内の名前付けされたプロパティにマッピングされている、要求されたクラスの新規インスタンスを返します。 PDO::FETCH_PROPS_LATE を指定していない限りは、カラムをマッピングしてからクラスのコンストラクタを呼び出します。 mode に PDO::FETCH_CLASSTYPE が含まれている場合 (例: PDO::FETCH_CLASS | PDO::FETCH_CLASSTYPE) は、最初のカラムの値からクラス名を決定します。
PDO::FETCH_INTO: 結果セットのカラムがクラス内の名前付けされたプロパティにマッピングされている要求された既存インスタンスを更新します。
PDO::FETCH_LAZY: PDO::FETCH_BOTH とPDO::FETCH_OBJの組合せで、アクセスされるオブジェクトプロパティ名を作成する PDORow オブジェクトを返します。
PDO::FETCH_NAMED: PDO::FETCH_ASSOC と同じ形式の配列を返します。ただし、同じ名前のカラムが複数あった場合は、そのキーが指す値は、同じ名前のカラムのすべての値を含む配列になります。
PDO::FETCH_NUM: 結果セットに返された際の 0 から始まるカラム番号を添字とする配列を返します。
PDO::FETCH_OBJ: 結果セットに返された際のカラム名と同名のプロパティを有する匿名のオブジェクトを返します。
PDO::FETCH_PROPS_LATE: PDO::FETCH_CLASS とともに使用すると、まずクラスのコンストラクタを呼び出してから、カラムの値をプロパティに代入します。

cursorOrientation

スクロール可能なカーソルを表す PDOStatement オブジェクトの場合、この値により呼び出し側に返される行を定義します。この値は、PDO::FETCH_ORI_* 定数のどれかとする必要があり、 PDO::FETCH_ORI_NEXT がデフォルトとなっています。 PDOStatement に対してスクロール可能なカーソルを要求するためには、 PDO::prepare() を用いて SQL ステートメントを準備する際、 PDO::CURSOR_SCROLL に PDO::ATTR_CURSOR 属性を設定する必要があります。

cursorOffset

スクロール可能なカーソルを表すPDOStatementオブジェクトの場合で、 cursorOrientation パラメータが PDO::FETCH_ORI_ABSに設定された場合、この値により取得される結果セットの行の絶対位置が指定されます。

スクロール可能なカーソルを表すPDOStatementオブジェクトの場合で、 cursorOrientation パラメータが PDO::FETCH_ORI_RELに設定された場合、この値は、 PDOStatement::fetch() がコールされる前のカーソルの位置を基準として取得する行の位置を指定します。

戻り値

この関数が成功した場合の戻り値は、取得形式によって異なります。失敗した場合、または行が残っていない場合は、常に false を返します。

エラー / 例外

PDO::ATTR_ERRMODE が PDO::ERRMODE_WARNING に設定されていた場合、E_WARNING レベルのエラーが発生します。

PDO::ATTR_ERRMODE が PDO::ERRMODE_EXCEPTION に設定されていた場合、PDOException がスローされます。

例

例1 異なる取得方法で行を取得する

<?php
$sth = $dbh->prepare("SELECT name, colour FROM fruit");
$sth->execute();

/* Exercise PDOStatement::fetch styles */
print "PDO::FETCH_ASSOC: ";
print "Return next row as an array indexed by column name\n";
$result = $sth->fetch(PDO::FETCH_ASSOC);
print_r($result);
print "\n";

print "PDO::FETCH_BOTH: ";
print "Return next row as an array indexed by both column name and number\n";
$result = $sth->fetch(PDO::FETCH_BOTH);
print_r($result);
print "\n";

print "PDO::FETCH_LAZY: ";
print "Return next row as a PDORow object with column names as properties\n";
$result = $sth->fetch(PDO::FETCH_LAZY);
print $result->name;
print "\n";

print "PDO::FETCH_OBJ: ";
print "Return next row as an anonymous object with column names as properties\n";
$result = $sth->fetch(PDO::FETCH_OBJ);
print $result->NAME;
print "\n";
?>

上の例の出力は以下となります。

PDO::FETCH_ASSOC: Return next row as an array indexed by column name
Array
(
    [name] => apple
    [colour] => red
)

PDO::FETCH_BOTH: Return next row as an array indexed by both column name and number
Array
(
    [name] => banana
    [0] => banana
    [colour] => yellow
    [1] => yellow
)

PDO::FETCH_LAZY: Return next row as a PDORow object with column names as properties
PDORow Object
(
    [name] => orange
    [colour] => orange
)

PDO::FETCH_OBJ: Return next row as an anonymous object with column names as properties
kiwi

例2 スクロール可能なカーソルで行を取得する

<?php
function readDataForwards($dbh) {
    $sql = 'SELECT hand, won, bet FROM mynumbers ORDER BY BET';
    $stmt = $dbh->prepare($sql, array(PDO::ATTR_CURSOR => PDO::CURSOR_SCROLL));
    $stmt->execute();
    while ($row = $stmt->fetch(PDO::FETCH_NUM, PDO::FETCH_ORI_NEXT)) {
        $data = $row[0] . "\t" . $row[1] . "\t" . $row[2] . "\n";
        print $data;
    }
}
function readDataBackwards($dbh) {
    $sql = 'SELECT hand, won, bet FROM mynumbers ORDER BY bet';
    $stmt = $dbh->prepare($sql, array(PDO::ATTR_CURSOR => PDO::CURSOR_SCROLL));
    $stmt->execute();
    $row = $stmt->fetch(PDO::FETCH_NUM, PDO::FETCH_ORI_LAST);
    do {
        $data = $row[0] . "\t" . $row[1] . "\t" . $row[2] . "\n";
        print $data;
    } while ($row = $stmt->fetch(PDO::FETCH_NUM, PDO::FETCH_ORI_PRIOR));
}

print "Reading forwards:\n";
readDataForwards($conn);

print "Reading backwards:\n";
readDataBackwards($conn);
?>

上の例の出力は以下となります。

Reading forwards:
21    10    5
16    0     5
19    20    10

Reading backwards:
19    20    10
16    0     5
21    10    5

例3 構築の順序

PDO::FETCH_CLASS でオブジェクトを取得するときには、まずオブジェクトのプロパティへの代入を終えてから、そのクラスのコンストラクタを実行します。 PDO::FETCH_PROPS_LATE を指定した場合はこの順序が逆転します。つまり、まずコンストラクタを呼び出してから、プロパティへの代入を行います。

<?php
class Person
{
    private $name;

    public function __construct()
    {
        $this->tell();
    }

    public function tell()
    {
        if (isset($this->name)) {
            echo "I am {$this->name}.\n";
        } else {
            echo "I don't have a name yet.\n";
        }
    }
}

$sth = $dbh->query("SELECT * FROM people");
$sth->setFetchMode(PDO::FETCH_CLASS, 'Person');
$person = $sth->fetch();
$person->tell();
$sth->setFetchMode(PDO::FETCH_CLASS|PDO::FETCH_PROPS_LATE, 'Person');
$person = $sth->fetch();
$person->tell();
?>

上の例の出力は、たとえば以下のようになります。

I am Alice.
I am Alice.
I don't have a name yet.
I am Bob.

参考

PDO::prepare() - 文を実行する準備を行い、文オブジェクトを返す
PDOStatement::execute() - プリペアドステートメントを実行する
PDOStatement::fetchAll() - 結果セットから、残っている行を取得する
PDOStatement::fetchColumn() - 結果セットの次行から単一カラムを返す
PDOStatement::fetchObject() - 次の行を取得し、それをオブジェクトとして返す
PDOStatement::setFetchMode() - この文に対するデフォルトのフェッチモードを設定する

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User Contributed Notes 22 notes

down

terry at bitsoup dot com ¶

18 years ago

WARNING:
fetch() does NOT adhere to SQL-92 SQLSTATE standard when dealing with empty datasets.

Instead of setting the errorcode class to 20 to indicate "no data found", it returns a class of 00 indicating success, and returns NULL to the caller.

This also prevents the exception mechainsm from firing.

Programmers will need to explicitly code tests for empty resultsets after any fetch*() instead of relying on the default behavior of the RDBMS.

I tried logging this as a bug, but it was dismissed as "working as intended". Just a head's up.

down

yarco dot wang at gmail dot com ¶

10 years ago

If no record, this function will also return false.
I think that is not very good...

down

henry at henrysmith dot org ¶

13 years ago

Someone's already pointed out that PDO::CURSOR_SCROLL isn't supported by the SQLite driver. It's also worth noting that it's not supported by the MySQL driver either.

In fact, if you try to use scrollable cursors with a MySQL statement, the PDO::FETCH_ORI_ABS parameter and the offset given to fetch() will be silently ignored. fetch() will behave as normal, returning rows in the order in which they came out of the database.

It's actually pretty confusing behaviour at first. Definitely worth documenting even if only as a user-added note on this page.

down

gergo at gergoerdosi dot com ¶

11 years ago

When using PDO::FETCH_COLUMN in a while loop, it's not enough to just use the value in the while statement as many examples show:

<?php
while ($row = $stmt->fetch(PDO::FETCH_COLUMN)) {
    print $row;
}
?>

If there are 5 rows with values 1 2 0 4 5, then the while loop above will stop at the third row printing only 1 2. The solution is to either explicitly test for false:

<?php
while (($row = $stmt->fetch(PDO::FETCH_COLUMN)) !== false) {
    print $row;
}
?>

Or use foreach with fetchAll():

<?php
foreach ($stmt->fetchAll(PDO::FETCH_COLUMN) as $row) {
    print $row;
}
?>

Both will correctly print 1 2 0 4 5.

down

lod ¶

16 years ago

A quick one liner to get the first entry returned.  This is nice for very basic queries.

<?php
$count = current($db->query("select count(*) from table")->fetch());
?>php

down

public at grik dot net ¶

13 years ago

When fetching an object, the constructor of the class is called after the fields are populated by default.



PDO::FETCH_PROPS_LATE is used to change the behaviour and make it work as expected - constructor be called _before_ the object fields will be populated with the data.



sample:



<?php

$a = $PDO->query('select id from table');

$a->setFetchMode(PDO::FETCH_CLASS|PDO::FETCH_PROPS_LATE, 'ClassName');

$obj = $a->fetch();

?>



http://bugs.php.net/bug.php?id=53394

down

Typer85 at gmail dot com ¶

14 years ago

Here is quick note for developers that use the PDO SQLite Driver:

The PDO SQLite driver does not support cursors, so using the PDO::CURSOR_SCROLL Attribute, will not work when using the PDO SQLite driver. For example:

<?php

// Assuming $Handle Is a PDO Handle.
$Statement = $Handle->query( $sqlStatement , array( PDO::ATTR_CURSOR => PDO::CURSOR_SCROLL ) );

?>

What is even worse is that PDO::prepare will NOT throw an Exception when it fails to prepare the query, even when the error mode is set to throw Exceptions, and will instead return a Boolean False!

Not only do I consider this a poor design choice, but also its a real shame that this is not documented anywhere in the manual -- in fact the manual is not clear on what Attributes are supported by which drivers and which are not so developers are left to play a classic game of guess.

I hope this saves some developers some headaches.

Good Luck,

down

paulf at quillandmouse dot com ¶

4 years ago

A prior poster indicated that this function returns a NULL when there are no results. This is not true. This function returns an empty array. fetchAll() returns the same.

Also, the documentation specifies what happens on "failure", but doesn't indicate what constitutes a "failure". A "failure" could be where the function returns no results; that is, the query "failed". However, a "failure" is apparently a situation where the PDO error functions would reveal a "failure", as in illegal SQL syntax, or a query on a table which doesn't exist, etc. An empty result is not a "failure". Maybe that's obvious to everyone else, but it wasn't to me.

down

Gerard van Beek ¶

17 years ago

If you to use a new instance of a class for a record you can use:

<?php
include_once("user.class");
$sth = $db->prepare("SELECT * FROM user WHERE id = 1");

/* create instance automatically */
$sth->setFetchMode( PDO::FETCH_CLASS, 'user');
$sth->execute();
$user = $sth->fetch( PDO::FETCH_CLASS );
$sth->closeCursor();
print ($user->id);

/* or create an instance yourself and use it */
$user= new user();
$sth->setFetchMode( PDO::FETCH_INTO, $user);
$sth->execute();
$user= $sth->fetch( PDO::FETCH_INTO );
$sth->closeCursor();
print ($user->id);
?>

down

lenz_kappov at yahoo dot co dot uk ¶

10 years ago

Because MySQL does not currently support the use of cursors, the $cursor_offset feature cannot work when using PDO to access a MySQL database.

If you are tring to arbitrarily access a specific record or group of records in a MySQL database recordset, you might want to consider using the LIMIT clause of the SELECT statement to achieve this e.g. LIMIT 5,3 to return just the 6th,7th & 8th records - 3 records starting at index 5 (which is the 6th record).

down

fh at ez dot no ¶

18 years ago

I can also add that the constructor is run _after_ the data is set on the object if yo use PDO::FETCH_CLASS.

down

fh at ez dot no ¶

18 years ago

If you want to use PDO::FETCH_CLASS you need to set it up with setFetchMode first like so:
        $stmt->setFetchMode( PDO::FETCH_CLASS, 'classType', array( 'parameters to constructor' );
        $object = $stmt->fetch( PDO::FETCH_CLASS );
If you ommit this PHP will segfault.

down

Black Knight ¶

8 years ago

this is just On reminder note about Second parameter -cursor_oriantation-

PDO::FETCH_ORI_NEXT :-
Fetch the next row in the result set. Valid only for scrollable cursors.

PDO::FETCH_ORI_PRIOR :-
Fetch the previous row in the result set. Valid only for scrollable cursors.

PDO::FETCH_ORI_FIRST :-
Fetch the first row in the result set. Valid only for scrollable cursors.

PDO::FETCH_ORI_LAST :-
Fetch the last row in the result set. Valid only for scrollable cursors.

PDO::FETCH_ORI_ABS :-
Fetch the requested row by row number from the result set. Valid only for scrollable cursors.

PDO::FETCH_ORI_REL :- 
Fetch the requested row by relative position from the current position of the cursor in the result set. Valid only for scrollable cursors.

down

Drew ¶

4 years ago

When using a PDOStatement with the fetch mode set to FETCH_CLASS, fetch will return false if no rows were found.

down

marcini ¶

17 years ago

Be careful with fetch() when you use prepared statements and MySQL (I don`t know how it is with other databases). Fetch won`t close cursor and won`t let you send any other query, even if your result set has only one row, . 
If you use $statement->fetch(), you will also have to use $statement->closeCursor() afterwards, to be albe to execute another query.
Alternatively you can use $statement->fetchAll() without $statement->closeCursor().

down

-2

Alex ¶

13 years ago

It seems that if you do a $statement->query() with an INSERT statement and after that a $statement->fetch() you will get an exception saying: SQLSTATE[HY000]: General error.

down

-1

lozitskiys at gmail dot com ¶

16 years ago

I spent some hours trying to find out how to manipulate with BLOB fields using PDO.

Remember that you can't retreive BLOB data using something like this :

<?php
$sql = 'SELECT * FROM sometable LIMIT 1';
$stmt = $dbh->prepare($sql);
$stmt->execute();
$stmt->setAttribute(PDO::FETCH_ASSOC);
$row = $stmt->fetch();

$myFile = $row['file'];
?>

Instead of this you should try following approach:

<?php
$sql = "SELECT mime, file FROM sometable LIMIT 1"; 
$stmt = $dbh->prepare($sql); 
$stmt->execute(); 

$stmt->bindColumn(1, $mime,); 
$stmt->bindColumn(2, $file, PDO::PARAM_LOB); 

$stmt->fetch(); 

header('Content-type: '.$mime);
print $file; 

?>

down

-2

tastro ¶

10 years ago

Note that this way, the "fetch mode" will get "overwritten", and PDO::FETCH_PROPS_LATE won't be applied:

<?php
$sth = $db->prepare("SELECT * FROM user WHERE id = 1");
$sth->setFetchMode( PDO::FETCH_CLASS|PDO::FETCH_PROPS_LATE, 'user');
$sth->execute();
$user = $sth->fetch( PDO::FETCH_CLASS );
$sth->closeCursor();
?>

Instead, you should leave the parameter area for the fetch() method empty, like this (if you want to set the fetch mode with the setFetchMode() method):

<?php
$sth = $db->prepare("SELECT * FROM user WHERE id = 1");
$sth->setFetchMode( PDO::FETCH_CLASS|PDO::FETCH_PROPS_LATE, 'user');
$sth->execute();
$user = $sth->fetch();
$sth->closeCursor();
?>

down

-3

sumariva at gmail dot com ¶

12 years ago

I could use PDO::FETCH_COLUMN to retrieve the first column from result.
$ps->fetch( PDO::FETCH_COLUMN );
Worked on Postgresql with PHP 5.3.10.

down

-2

aledmb at gmail dot com ¶

19 years ago

note that fetch constants are not included in the PDO class for PHP versions prior to 5.1

down

-4

josh ¶

16 years ago

Note that PDO::ATTR_STRINGIFY_FETCHES will NOT work for the MySQL driver. MySQL will always return strings because that is the behaviour of the core mysql PHP extension. See http://bugs.php.net/bug.php?id=44341

down

-4

tim at kooky dot org ¶

8 years ago

Be careful when using PDO::FETCH_LAZY.  It adds an additional field called queryString.  I'm not sure if this a bug or not. I'm using version 5.6.17 in Debian Jessie.

Query:  'select 1,2,3'

$row=$smt->fetch(PDO::FETCH_OBJ);
var_dump($row);

object(stdClass)#6 (3) {
  ["1"]=>
  string(1) "1"
  ["2"]=>
  string(1) "2"
  ["3"]=>
  string(1) "3"
}

$row=$smt->fetch(PDO::FETCH_LAZY);
var_dump($row);

object(PDORow)#3 (4) {
  ["queryString"]=>
  string(12) "select 1,2,3"
  ["1"]=>
  string(1) "1"
  ["2"]=>
  string(1) "2"
  ["3"]=>
  string(1) "3"
}

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