fetchColumn return boolean false when a row not is found or don't had more rows.
PDOStatement::fetchColumn
(PHP 5 >= 5.1.0, PHP 7, PECL pdo >= 0.9.0)
PDOStatement::fetchColumn — Returns a single column from the next row of a result set
Descrierea
Returns a single column from the next row of a result set or false if
there are no more rows.
Notă:
PDOStatement::fetchColumn() should not be used to retrieve boolean columns, as it is impossible to distinguish a value of
falsefrom there being no more rows to retrieve. Use PDOStatement::fetch() instead.
Parametri
-
column_number -
0-indexed number of the column you wish to retrieve from the row. If no value is supplied, PDOStatement::fetchColumn() fetches the first column.
Valorile întoarse
PDOStatement::fetchColumn() returns a single column
from the next row of a result set or false if there are no more rows.
Avertizare
There is no way to return another column from the same row if you use PDOStatement::fetchColumn() to retrieve data.
Exemple
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");
?>
Exemplul de mai sus va afișa:
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
A se vedea și
- PDO::query() - Executes an SQL statement, returning a result set as a PDOStatement object
- PDOStatement::fetch() - Fetches the next row from a result set
- PDOStatement::fetchAll() - Returns an array containing all of the result set rows
- PDO::prepare() - Prepares a statement for execution and returns a statement object
- PDOStatement::setFetchMode() - Set the default fetch mode for this statement
add a note
User Contributed Notes 3 notes
PhoneixSegovia at GOOGLE_MAIL_SERVER dot com ¶
14 years ago
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.
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".
