mongodb（不一样的sql）

db.selectname.find({}).count()

db.shiXinPeople.find({}).count()

/*

*复合索引唯一

*db.People.ensureIndex({"Name":1,"Age":1},{"unique":true,"dropDups":true})

*/

db.selectname.ensureIndex({"selectName":1,"city":1},{"unique":true,"dropDups":true})

db.shiXinPeople.ensureIndex({"loc":1},{"unique":true,"dropDups":true})

/*

*update 更新操作

*db.classes.update({"count":{$gt:20}},{$set:{"name":"c4"}},false,true)

*/

db.selectname.find({"selectState" : "0"}).limit(2)

db.selectname.update({},{"$set":{"start":0,"selectState":"0"}},false,true)

db.selectname.update({},{"$unset":{"SelectState":""}},false,true)

db.selectname.update({},{$set:{"selectState":"0"}},false,true)

db.selectname.aggregate({"$group":{"_id":{"selectState":"$selectState"},"count":{$sum:1}}})

db.selectname.find({"selectState":"1","start":{$gte:1000}})

db.selectname.find({"selectState":"1"})

db.shiXinPeople.find({}).count()

db.shiXinPeople.distinct('loc')

db.shiXinPeople.aggregate([{"$group":{"_id":{"loc":"$loc"},"count":{$sum:1}}},{"$match":{"count" : {"$gt" : 1}}}],{ allowDiskUse: true })