Php/docs/mongodb.command
MongoDB::command
(PECL mongo >=0.9.2)
MongoDB::command — 执行一条 Mongo 指令
说明
public MongoDB::command
( array $command
[, array $options = array()
] ) : array
几乎所有不属于CRUD操作的事情都可以通过一条“数据库指令”完成。需要知道数据库的版本？有一条指令可以实现。需要进行一次聚合？有一条指令可以实现。想要提高日志级别？有一条指令可以实现。我想你已经领会到了。
该方法等同于：
<?phppublic function command($data) { return $this->selectCollection('$cmd')->findOne($data);}?>
参数
command要发送的指令
options该参数是一个具有以下形式的关联数组：
array("optionname" => <boolean>, ...)，现在支持的选项有："timeout"Deprecated alias for
"socketTimeoutMS".
更新日志
| 版本 | 说明 |
|---|---|
| 1.2.0 | 添加 options 参数，和一个选项:"timeout"。
|
返回值
返回数据库响应。每个响应都不会超过一个文档的大小，也就是不会超过16MB。
结果文档的结构与执行的指令有关,但大部分结果都有
ok 字段来表示成功还是失败。以及
results 字段包含一个结果文档数组。
范例
Example #1 MongoDB::command() "distinct"实例
查找一个键的所有不重复值
<?php$people = $db->people;$people->insert(array("name" => "Joe", "age" => 4));$people->insert(array("name" => "Sally", "age" => 22));$people->insert(array("name" => "Dave", "age" => 22));$people->insert(array("name" => "Molly", "age" => 87));$ages = $db->command(array("distinct" => "people", "key" => "age"));foreach ($ages['values'] as $age) { echo "$age\n";}?>
以上例程的输出类似于：
4 22 87
Example #2 MongoDB::command() "distinct"实例
查找一个键的所有不重复值，并且这些值大于等于18
<?php$people = $db->people;$people->insert(array("name" => "Joe", "age" => 4));$people->insert(array("name" => "Sally", "age" => 22));$people->insert(array("name" => "Dave", "age" => 22));$people->insert(array("name" => "Molly", "age" => 87));$ages = $db->command( array( "distinct" => "people", "key" => "age", "query" => array("age" => array('$gte' => 18)) )); foreach ($ages['values'] as $age) { echo "$age\n";}?>
以上例程的输出类似于：
22 87
Example #3 MongoDB::command() MapReduce实例
获取所有有type=sale这样的"event"的用户，以及他们分别有几个这样的"event"（注:此处的event是一个集合的名字）
<?php// sample event document$events->insert(array("user_id" => $id, "type" => $type, "time" => new MongoDate(), "desc" => $description));// construct map and reduce functions$map = new MongoCode("function() { emit(this.user_id,1); }");$reduce = new MongoCode("function(k, vals) { ". "var sum = 0;". "for (var i in vals) {". "sum += vals[i];". "}". "return sum; }");$sales = $db->command(array( "mapreduce" => "events", "map" => $map, "reduce" => $reduce, "query" => array("type" => "sale"), "out" => array("merge" => "eventCounts")));$users = $db->selectCollection($sales['result'])->find();foreach ($users as $user) { echo "{$user['_id']} had {$user['value']} sale(s).\n";}?>
以上例程的输出类似于：
User 47cc67093475061e3d9536d2 had 3 sale(s). User 49902cde5162504500b45c2c had 14 sale(s). User 4af467e4fd543cce7b0ea8e2 had 1 sale(s).
Note:
使用 MongoCode
这个例子使用了 MongoCode，它还可以接受一个作用域参数。然而，现在 MongoDB 还不支持在 MapReduce 中使用它， 如果你需要在MapReduce函数里用一个客户端参数，那么你可以在使用MapReduce的时候用“optional scope”字段把它们添加到全局作用域中，参考 » MapReduce文档 来获得更多信息。
Note:
out参数1.8.0以前，
out参数是可选的，如果你不使用它，MapReduce的结果将被写入一个临时集合里，这个临时集合会在连接关闭后删除。 1.8.0以后，out参数是必须的，参考 » MapReduce documentation 来获得更多信息。
Example #4 MongoDB::command() "textSearch"实例
在MongoDB 2.4以上版本中使用全文检索功能（之前的版本不支持全文检索）。
<?php$m = new MongoClient();$d = $m->demo;$c = $d->planets;$c->insert(array("name" => "Mercury", "desc" => "Mercury is the smallest and closest to the Sun"));$c->insert(array("name" => "Venus", "desc" => "Venus is the second planet from the Sun, orbiting it every 224.7 Earth days."));$c->insert(array("name" => "Earth", "desc" => "Earth is the the densest of the eight planets in the Solar System."));$c->insert(array("name" => "Mars", "desc" => "Mars is named after the Roman god of war."));$c->ensureIndex(array('desc' => 'text'));$r = $d->command(array("text" => "planets", 'search' => "sun" ));print_r($r);?>
以上例程的输出类似于：
Array ( [queryDebugString] => sun|||||| [language] => english [results] => Array ( [0] => Array ( [score] => 0.625 [obj] => Array ( [_id] => MongoId Object ( [$id] => 517549d944670a4a5cb3059a ) [name] => Mercury [desc] => Mercury is the smallest and closest to the Sun ) ) [1] => Array ( [score] => 0.55 [obj] => Array ( [_id] => MongoId Object ( [$id] => 517549d944670a4a5cb3059b ) [name] => Venus [desc] => Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. ) ) ) [stats] => Array ( [nscanned] => 2 [nscannedObjects] => 0 [n] => 2 [nfound] => 2 [timeMicros] => 95 ) [ok] => 1 )
Example #5 MongoDB::command() "geoNear"实例
这个实例说明了如何使用 geoNear 指令。
<?php$m = new MongoClient();$d = $m->demo;$c = $d->poiConcat;$r = $d->command(array( 'geoNear' => "poiConcat", // 在 poiConcat 集合中 'near' => array(-0.08, 51.48), // 搜索 51.48°N, 0.08°E 附近 'spherical' => true, // 启用特殊搜索 'num' => 5, // 最多返回5个文档));print_r($r);?>
参见
- MongoCollection::aggregate() - Perform an aggregation using the aggregation framework
- MongoCollection::findAndModify() - Update a document and return it
- MongoCollection::group() - Performs an operation similar to SQL's GROUP BY command
MongoDB 核心文档的 » 数据库指令 ，以及这些特定指令的文档 » findAndModify、 » getLastError、 » repairDatabase （还有很多其他指令，这只是一些例子）
