(PECL mongo >=0.9.0)
MongoCollection::findOne — Querys this collection, returning a single element
The fields for which to search.
Fields of the results to return.
Returns record matching the search or NULL.
Throws MongoConnectionException if it cannot reach the database.
Example #1 MongoCollection::findOne() document by its id.
This example demonstrates how to find a single document in a collection by its id.
<?php
$articles = $mongo->my_db->articles;
$article = $articles->findOne(array('_id' => new MongoId('47cc67093475061e3d9536d2')));
?>
Example #2 MongoCollection::findOne() document by some condition.
This example demonstrates how to find a single document in a collection by some condition and limiting the returned fields.
<?php
$users = $mongo->my_db->users;
$user = $users->findOne(array('username' => 'jwage'), array('password'));
print_r($user);
?>
以上例程的输出类似于：
Array
(
[_id] => MongoId Object
(
)
[password] => test
)
Notice how even though the document does have a username field, we limited the results to only contain the password field.