mongo中mysql max和min函数的等价物？

Question

我如何在mongo中编写下面的查询？

select max(priority) as max, min(priority) as min from queue group by user 

如果您在PHP中提供解决方案，我将非常感激。

谢谢

Answer 1

查询像这样与聚集framwework和.aggregate()方法进行。他们使用$group流水线阶段与$min和$max运营商。

db.collection.aggregate([ 
    { "$group": { 
     "_id": "$user", 
     "max": { "$max": "$priority" }, 
     "min": { "$min": "$priority" } 
    }} 
]) 

以上PHP语法：

$collection->aggregate(array(
    array(
     '$group' => array (
      '_id' => '$user', 
      'max' => array('$max' => '$priority'), 
      'min' => array('$min' => '$priority') 
     ) 
    ) 
)); 

另见SQL to Aggregation Mapping Chart文档中