一个名为test的、和集合
考虑此测试集合,其中机场由AirportID标识:
{ AirportID:"1001", delayMinutes :"15.0" },
{ AirportID:"1004", delayMinutes :"3.0" },
{ AirportID:"1001", delayMinutes :"20.0" },
{ AirportID:"1002", delayMinutes :"6.0" },
{ AirportID:"1002", delayMinutes :"25.0" },
{ AirportID:"1004", delayMinutes :"55.0" },
我想把它组合在一起,列出列表中的前2个.
这是我try 的查询:
db.test.aggregate([
{ $group: { _id: "$AirportID", delayMinutes: { $sum: 1 } } },
{ $sort: { delayMinutes: -1 } }
])
但这对我没用