mongodb聚合查询aggregation pipeline示例

参考来源，mongodb官网文档
示例说明
我们以2019第一季度基金重仓股票数据为例，查询2019基金重仓股票排行

数据截图

聚合语句

db.fund_stock.aggregate([
    {
        $match: {  
            currentYear: "2019"
        }
    },
    {
        $group: {    
            _id: "$stockCode",     
			stockName:{$first:"$stockName"},
            num_tutorial: { 
                $sum: 1
            },
			currentYear:{$first:"$currentYear"},
			fundCodes:{$push:"$fundCode"}
        }
    },
    {
        $sort: {
            num_tutorial: -1
        }
    },
		{
			$project:{
			   _id:false,
				 stockCode:"$_id",
				 stockName: "$stockName",
				 coun:"$num_tutorial",
				  currentYear:"$currentYear",
				 fundCodes:"$fundCodes"
			}
		}
])

输出结果