摘要:
mapreduce 阅读全文
posted @ 2017-03-21 10:15
jay-
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摘要:
1.db.companies.aggregate({"$project":{"companyId":1,"_id":0}}) //在查询的结果中,只出现companyId结果 2.db.companies.aggregate({"$group":{"_id":"$companyId","count" 阅读全文
posted @ 2017-03-21 10:13
jay-
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