SUM() in Mongodb? Issue with Query?

Question

I am trying to write a PHP (Mongo) query from SQL in which I have SUM() but I am not sure my syntax is correct. Can someone enlighten me?

SQL:

$cmd = "SELECT SUM(m_length) FROM pkt_tbl WHERE m_time>=" . $time. " AND m_buffer_latency<=" . $time;

Mongodb Query:

    $find_projection= aggregate(array('$group'=>array('$sum'=>'$m_length')));
    $result = $table -> command($find_projection);

Can I use array_sum is the $result or is there anyway I can use $SUM (Aggregate) in this case. Any help would be appreciated.

Thanks

Rohan Kumar · Accepted Answer · 2013-07-19 04:33:11Z

3

You should try aggregation

In php this code may help you,

<?php
    $m = new Mongo;
    $c = $m->selectDB("test")->selectCollection("zips");

    $out = $c->aggregate(array(
            '$group' => array(
                '_id' => '$state',
               'totalPop' => array('$sum' => '$pop')
            )
        ),
        array(
            '$match' => array('totalPop' => array('$gte' => 10*1000*1000))
        )
    );

    var_dump($out);
?>

Mongocollection Aggregate

answered Jul 19, 2013 at 4:33

Rohan Kumar

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5 Comments

iron man Over a year ago

Thanks for your inputs. Any suggestions regarding my query would be appreciated. Can you check my query? I used array_sum in $result, can I implement like that?

Rohan Kumar Over a year ago

array_sum gets an array as a parameter to calculate the sum like array_sum(array(2,4,8,6)); but check what are you passing in it? Passing array('m_length' => 1) to array_sum makeing some sense? Read this php.net/manual/en/function.array-sum.php

iron man Over a year ago

hmm I thought passing $find_projection which is array('m_length'=>1 would be considered an array(since it's array()) . can you enlighten me as to how to change my query then?

Rohan Kumar Over a year ago

Read this stackoverflow.com/questions/8874671/… and docs.mongodb.org/manual/reference/method/db.collection.group it may help you.

iron man Over a year ago

Alright. I have tried to use aggregate, Still am not getting the issue. Can someone check my syntax? $find_projection= aggregate(array('$group'=>array('$sum'=>'$m_length'))); $result = $table -> command($find_projection)

iron man · Accepted Answer · 2013-07-20 00:58:26Z

0

$result = $table->aggregate(
array('$match' => array(
'm_time' => array('$gte' => $max),
'm_buffer_latency' => array('$lte' => $max),
)),
array('$group' => array(
'_id' => true,
'sum_length' => array('$sum' => '$m_length')
))
);

This answers it all

answered Jul 20, 2013 at 0:58

iron man

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