Controls the contents of the returned array as documented in PDOStatement::fetch(). Defaults to value of PDO::ATTR_DEFAULT_FETCH_MODE (which defaults to PDO::FETCH_BOTH)
To return an array consisting of all values of a single column from the result set, specify PDO::FETCH_COLUMN. You can specify which column you want with the fetch_argument parameter.
To fetch only the unique values of a single column from the result set, bitwise-OR PDO::FETCH_COLUMN with PDO::FETCH_UNIQUE.
To return an associative array grouped by the values of a specified column, bitwise-OR PDO::FETCH_COLUMN with PDO::FETCH_GROUP.
This argument has a different meaning depending on the value of the fetch_style parameter:
-
PDO::FETCH_COLUMN: Returns the indicated 0-indexed column. -
PDO::FETCH_CLASS: Returns instances of the specified class, mapping the columns of each row to named properties in the class. -
PDO::FETCH_FUNC: Returns the results of calling the specified function, using each row's columns as parameters in the call.
Arguments of custom class constructor when the fetch_style parameter is PDO::FETCH_CLASS.
PDOStatement::fetchAll() returns an array containing all of the remaining rows in the result set. The array represents each row as either an array of column values or an object with properties corresponding to each column name. An empty array is returned if there are zero results to fetch, or FALSE on failure.
Using this method to fetch large result sets will result in a heavy demand on system and possibly network resources. Rather than retrieving all of the data and manipulating it in PHP, consider using the database server to manipulate the result sets. For example, use the WHERE and ORDER BY clauses in SQL to restrict results before retrieving and processing them with PHP.
<?php
$sth = $dbh->prepare("SELECT name, colour FROM fruit");
$sth->execute();
/* Fetch all of the remaining rows in the result set */
print("Fetch all of the remaining rows in the result set:\n");
$result = $sth->fetchAll();
print_r($result);
?>
The above example will output something similar to:
Fetch all of the remaining rows in the result set:
Array
(
[0] => Array
(
[name] => pear
[0] => pear
[colour] => green
[1] => green
)
[1] => Array
(
[name] => watermelon
[0] => watermelon
[colour] => pink
[1] => pink
)
)
The following example demonstrates how to return all of the values of a single column from a result set, even though the SQL statement itself may return multiple columns per row.
<?php
$sth = $dbh->prepare("SELECT name, colour FROM fruit");
$sth->execute();
/* Fetch all of the values of the first column */
$result = $sth->fetchAll(PDO::FETCH_COLUMN, 0);
var_dump($result);
?>
The above example will output something similar to:
Array(3)
(
[0] =>
string(5) => apple
[1] =>
string(4) => pear
[2] =>
string(10) => watermelon
)
The following example demonstrates how to return an associative array grouped by the values of the specified column in the result set. The array contains three keys: values apple and pear are returned as arrays that contain two different colours, while watermelon is returned as an array that contains only one colour.
<?php
$insert = $dbh->prepare("INSERT INTO fruit(name, colour) VALUES (?, ?)");
$insert->execute(array('apple', 'green'));
$insert->execute(array('pear', 'yellow'));
$sth = $dbh->prepare("SELECT name, colour FROM fruit");
$sth->execute();
/* Group values by the first column */
var_dump($sth->fetchAll(PDO::FETCH_COLUMN|PDO::FETCH_GROUP));
?>
The above example will output something similar to:
array(3) {
["apple"]=>
array(2) {
[0]=>
string(5) "green"
[1]=>
string(3) "red"
}
["pear"]=>
array(2) {
[0]=>
string(5) "green"
[1]=>
string(6) "yellow"
}
["watermelon"]=>
array(1) {
[0]=>
string(5) "green"
}
}
The following example demonstrates the behaviour of the PDO::FETCH_CLASS fetch style.
<?php
class fruit {
public $name;
public $colour;
}
$sth = $dbh->prepare("SELECT name, colour FROM fruit");
$sth->execute();
$result = $sth->fetchAll(PDO::FETCH_CLASS, "fruit");
var_dump($result);
?>
The above example will output something similar to:
array(3) {
[0]=>
object(fruit)#1 (2) {
["name"]=>
string(5) "apple"
["colour"]=>
string(5) "green"
}
[1]=>
object(fruit)#2 (2) {
["name"]=>
string(4) "pear"
["colour"]=>
string(6) "yellow"
}
[2]=>
object(fruit)#3 (2) {
["name"]=>
string(10) "watermelon"
["colour"]=>
string(4) "pink"
}
}
The following example demonstrates the behaviour of the PDO::FETCH_FUNC fetch style.
<?php
function fruit($name, $colour) {
return "{$name}: {$colour}";
}
$sth = $dbh->prepare("SELECT name, colour FROM fruit");
$sth->execute();
$result = $sth->fetchAll(PDO::FETCH_FUNC, "fruit");
var_dump($result);
?>
The above example will output something similar to:
array(3) {
[0]=>
string(12) "apple: green"
[1]=>
string(12) "pear: yellow"
[2]=>
string(16) "watermelon: pink"
}
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