There are a few problems.  First, you need to quote '2010-03' or PHP will interpret it as 2007 (2010 *minus* 03).  Since you are only using one metadata name/value pair, you also should change that call to:

'metadata_name_value_pair' => array('name' => ...)

or:

'metadata_name_value_pairs' => array(array('name' => ...))

The second statement has a typo in the 'metadata_values' field, and probably doesn't do exactly what you want because name isn't available metadata for a user.  (Using multiple names and values doesn't do what you want in this case anyway--It's an OR statement instead of an AND.  Use metadata_name_value_pairs.)  I'm not sure what you want the second call to return...

You might want to review the documentation on the metadata system: http://docs.elgg.org/wiki/Engine/DataModel/Metadata

Brett, I finnally get it works like this:

 elgg_get_entities_from_metadata(array('types'=>'object', 'subtypes'=>'selldata', 'limit'=>1, 'metadata_names' =>array('name','month'), 'metadata_values' =>array($name,$month), 'owner_guid'=>get_loggedin_userid()));

Thanks.

Glad it's working for you but there are a still a few problems:

First, this statement will fail if a non-logged in user looks at that page--It will either return nothing or return all matches ignoring the owner.  Make sure you put a check to see if the user is logged in before calling this function.

Second, use metadata_name_value_pairs.  This statement doesn't do what you want and only works by chance.  The SQL generated by this statement will be something like:

... WHERE metadata_name IN ('name', 'month') AND metadata_value IN ('$name', '$month') ...

You want SQL to be:

... WHERE (metadata_name1 = 'name' AND metadata_value1 = '$name') AND (metadata_name2 = 'month' AND metadata_value2 = '$month)

A name/value pair will look like:

'metadata_name_value_pair' => array(

    array('name' => 'name', 'value' => $name),

    array('name' => 'month', 'value' => $month)

)

...and will generate what you want.

Thanks your suggestion and guidance, Brett.

I found this function not work indeed.

for example: if there are 3 entities, only one entity match what I need, and the other two are empty. the function will also return 3 result, but the other two will use the value of the match one.

I had even tested Brett's suggestion, not work too:

'metadata_name_value_pair' => array(

    array('name' => 'name', 'value' => $name),

    array('name' => 'month', 'value' => $month)

)

The following is my current codes:

 elgg_get_entities_from_metadata(array('types'=>'object', 'subtypes'=>'selldata', 'limit'=>1, 'metadata_names' =>array('name','month'), 'metadata_values' =>array($name,$month), 'owner_guid'=>get_loggedin_userid()));

It seems that either $name or $month matches, the results will be returned.

If the datas are:

name | sell | month
John | 200 | 2010-03
Simon| 100 | 2010-03
King | 300 | 2010-03
John | 123 | 2010-02

if I want to get entity with $name='John' and $month='2010-03', the result returns:

sell:200
sell:200
sell:200

@jdleung - It's very hard to help debug this because we don't know how your plugin saves its data.  Can you post the code you're using to save information?

Brett, here is it

// get the form input
$name = get_input('name');
$month = get_input('month');
$sell = get_input('sell');
$pv = get_input('pv');
$i=0;
  
foreach($name as $item){

    // create a new blog object
    $insertdata = new ElggObject(); 
   
    $insertdata->title = $name[$i];
    $insertdata->name = $name[$i];
    $insertdata->description = $month;
    $insertdata->month = $month;
    $insertdata->sell = $sell[$i];
    $insertdata->pv = $pv[$i];
    $insertdata->subtype = "selldata";

    // for now make all blog posts public
    $insertdata->access_id = 0;

    // owner is logged in user
    $insertdata->owner_guid = get_loggedin_userid();

    // save to database
    $insertdata->save();
   
    $i++;
}

$name, $sell and $pv are array, since the design is one form for multi input.

It takes me a long time to get it really works now, a 'operand' => '=' is needed!

'metadata_name_value_pair' => array(

    array('name' => 'name', 'value' => $name, 'operand' => '=' ),

    array('name' => 'month', 'value' => $month, 'operand' => '=' )

)

I realize this thread is old - but it is one of the top google results on this topic.  The code for v1.7.8 should be "metadata_name_value_pairs" not "metadata_name_value_pair".