MongoDB / PHP ..如何编写选择查询？

Question

How to write find query in mongo db to select certain values. For example

IN MYSQL - SELECT * from things where id=3;
IN Mongo - thingscollection->find(array("_id" => $id))

suppose if the MYSQL query looks like this,

SELECT name,age from things where id=3;

I am wondering how to write find query in PHP/MongoDB to select specific values?

Answer 1

MySQL: SELECT name,age from things where id=3;  
Mongo: $db->things->find(array("id" => 3), array("name" => 1, "age" => 1));

You may want to use the mongo _id instead of an own created id field.

For more information specifically about the php driver: http://php.net/manual/en/mongo.sqltomongo.php An other good link for just SQL to Mongo is http://rickosborne.org/download/SQL-to-MongoDB.pdf

Answer 2

在Mongo语句中编写查询时，使用SQL作为参考。

Answer 3

您可以从PHP在线手册中找到SQL to Mongo Mapping Chart 。

Answer 4

Yogesh suggested using the mongo _id but that actually is more complicated than a regular field in the document.

To achieve:

IN MYSQL - SELECT * from things where id=3;

using MongoDB's PHP driver, do this:

$m = new MongoClient();
$db = $m->selectDB('stuff');
$collection = new MongoCollection($db, 'things');
$collection->find(array('_id', new MongoID('3'));

If you didn't save your document with an "_id" field, then Mongo adds this field automatically, with a BSON value that has a very high probability of being unique. It's usually something like '512ba941e0b975fe00000000'.

If you try to $collection->find(array('_id' => '512ba941e0b975fe00000000')); the results are empty and no error is generated, which can be extremely frustrating while debugging. It's easy to forget to use new MongoID() and not simply the string _id .

Answer 5

$mongo_url = 'mongodb://127.0.0.1/';
$client = new \MongoDB\Client($mongo_url);
$db_name = 'your_db_name';
$db = $client->$db_name;
$collection = $db->your_collection_name;

$where = array(
    'user_id' => 3
);
$select_fields = array(
    'name' => 1,
    'age' => 1,
);
$options = array(
    'projection' => $select_fields
);
$cursor = $collection->find($where, $options);   //This is the main line
$docs = $cursor->toArray();

print_r($docs);