MongoDB——分页排序聚合操作
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MongoDB——分页排序聚合操作
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原始數(shù)據(jù):
/* 1 */ {"_id" : ObjectId("5b604ac423cc834a5495d780"),"name" : "lhc","age" : 78.0 }/* 2 */ {"_id" : ObjectId("5b6068c94b008f4e969ef4fd"),"name" : "jay","age" : 20.0 }/* 3 */ {"_id" : ObjectId("5b6068cf4b008f4e969ef4fe"),"name" : "aaa","age" : 10.0 }/* 4 */ {"_id" : ObjectId("5b6068d64b008f4e969ef4ff"),"name" : "bbbb","age" : 88.0 }/* 5 */ {"_id" : ObjectId("5b6068de4b008f4e969ef500"),"name" : "weeee","age" : 0.0 }/* 6 */ {"_id" : ObjectId("5b6068e54b008f4e969ef501"),"name" : "weeee","age" : 30.0 }skip & limit
db.user.find().limit(1).skip(1); /* 1 */ {"_id" : ObjectId("5b6068c94b008f4e969ef4fd"),"name" : "jay","age" : 20.0 }sort
// 1 為升序排列,而 -1 是用于降序排列 db.user.find().sort({age:1}); /* 1 */ {"_id" : ObjectId("5b6068de4b008f4e969ef500"),"name" : "weeee","age" : 0.0 }/* 2 */ {"_id" : ObjectId("5b6068cf4b008f4e969ef4fe"),"name" : "aaa","age" : 10.0 }/* 3 */ {"_id" : ObjectId("5b6068c94b008f4e969ef4fd"),"name" : "jay","age" : 20.0 }/* 4 */ {"_id" : ObjectId("5b6068e54b008f4e969ef501"),"name" : "weeee","age" : 30.0 }/* 5 */ {"_id" : ObjectId("5b604ac423cc834a5495d780"),"name" : "lhc","age" : 78.0 }/* 6 */ {"_id" : ObjectId("5b6068d64b008f4e969ef4ff"),"name" : "bbbb","age" : 88.0 }聚合操作
aggregate用于聚合操作,語法格式:db.COLLECTION_NAME.aggregate(AGGREGATE_OPERATION),例如,求平均值:
db.user.aggregate([{$group:{_id:'$name',average:{$avg:'$age'}}}]);總結(jié)
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