PDOStatement::fetchColumn

(PHP 5 >= 5.1.0, PHP 7, PHP 8, PECL pdo >= 0.9.0)

PDOStatement::fetchColumn — Returns a single column from the next row of a result set

Descrizione

public PDOStatement::fetchColumn(int $column = 0): mixed

Returns a single column from the next row of a result set or false if there are no more rows.

Nota:
PDOStatement::fetchColumn() should not be used to retrieve boolean columns, as it is impossible to distinguish a value of false from there being no more rows to retrieve. Use PDOStatement::fetch() instead.

Elenco dei parametri

column: 0-indexed number of the column you wish to retrieve from the row. If no value is supplied, PDOStatement::fetchColumn() fetches the first column.

Valori restituiti

PDOStatement::fetchColumn() returns a single column from the next row of a result set or false if there are no more rows.

Avviso

There is no way to return another column from the same row if you use PDOStatement::fetchColumn() to retrieve data.

Errori/Eccezioni

Emits an error with level E_WARNING if the attribute PDO::ATTR_ERRMODE is set to PDO::ERRMODE_WARNING.

Throws a PDOException if the attribute PDO::ATTR_ERRMODE is set to PDO::ERRMODE_EXCEPTION.

Esempi

Example #1 Return first column of the next row

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

print "Fetch the first column from the first row in the result set:\n";
$result = $sth->fetchColumn();
print "name = $result\n";

print "Fetch the second column from the second row in the result set:\n";
$result = $sth->fetchColumn(1);
print "colour = $result\n";
?>

Il precedente esempio visualizzerà:

Fetch the first column from the first row in the result set:
name = lemon
Fetch the second column from the second row in the result set:
colour = red

Vedere anche:

PDO::query() - Prepares and executes an SQL statement without placeholders
PDOStatement::fetch() - Fetches the next row from a result set
PDOStatement::fetchAll() - Fetches the remaining rows from a result set
PDO::prepare() - Prepares a statement for execution and returns a statement object
PDOStatement::setFetchMode() - Set the default fetch mode for this statement

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User Contributed Notes 3 notes

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PhoneixSegovia at GOOGLE_MAIL_SERVER dot com ¶

14 years ago


fetchColumn return boolean false when a row not is found or don't had more rows.

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seanferd at assmasterdonkeyranch dot com ¶

17 years ago


This is an excellent method for returning a column count. For example:



<?php

$db = new PDO('mysql:host=localhost;dbname=pictures','user','password');

$pics = $db->query('SELECT COUNT(id) FROM pics');

$this->totalpics = $pics->fetchColumn();

$db = null;

?>

In my case $pics->fetchColumn() returns 641 because that is how many pictures I have in my db.

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theking2(at)king.ma ¶

10 months ago


When migrating from mysqli it is important that while mysqli_result::fetch_column will iterate over subsequent rows  PDOStatement::fetchColumn will NOT!

<?php
while ( $row0 = $db->query("SELECT `value` FROM `bool`")->fetchColumn(0) ) {
  var_dump( $row0 );
}
?>

is an endless loop unless the first column in the first row of the table bool is "0".

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