MongoCollection::group

(PECL mongo >=0.9.2)

MongoCollection::group — Performs an operation similar to SQL's GROUP BY command

설명

public array MongoCollection::group ( array $keys , array $initial , string $reduce [, array $condition= array() ] )

인수

keys: Fields to group by.
initial: Initial value of the aggregation counter object.
reduce: A function that aggregates (reduces) the objects iterated.
condition: An condition that must be true for a row to be considered.

반환값

Returns an array containing the result.

예제

Example #1 MongoCollection::group() example


<?php

$collection->save(array("a" => 2));
$collection->save(array("b" => 5));
$collection->save(array("a" => 1));

// use all fields
$keys = array();

// set intial values
$initial = array("count" => 0);

// JavaScript function to perform
$reduce = "function (obj, prev) { prev.count++; }";

// only use documents where the "a" field is greater than 1
$condition = array("a" => array( '$gt' => 1));

$g = $collection->group($keys, $initial, $reduce, $condition);

var_dump($g);

?>

위 예제의 출력 예시:

array(1) {
  [0]=>
  array(1) {
    ["count"]=>
    int(1)
  }
}