Setting Criteria for a Query
Creating An Index
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PHP Manual

## Getting A Set of Documents With a Query

We can use the query to get a set of documents from our collection. For example, if we wanted to get all documents where "i" > 50, we could write:

`<?php
$connection = new MongoClient();
$collection = $connection->database->collectionName;
$query = array( "i" => array( '$gt' => 50 ) ); //note the single quotes around '$gt'
$cursor = $coll->find( $query );
while ( $cursor->hasNext() )
{
var_dump( $cursor->getNext() );
}
?>`

which should print the documents where "i" > 50. We could also get a range, say 20 < i <= 30:

    <?php
    $connection = new MongoClient();
    $collection = $connection->database->collectionName;

    $query = array( 'i' => array( '$gt' => 20, "\$lte" => 30 ) );
    $cursor = $coll->find( $query );

    while ( $cursor->hasNext() )
    {
        var_dump( $cursor->getNext() );
    }
    ?>

Remember to always escape the $-symbol or use single quotes. Otherwise PHP will interpret it to be the variable $gt.