MongoDB 查询操作的实例详解

mongos> db.blog.find({},{“name”:1}) 
{ “_id” : ObjectId(“5659836e73c8340448fa470e”) } 
{ “_id” : ObjectId(“565e5c0e73c8340448fa470f”) } 
{ “_id” : ObjectId(“565f998e73c8340448fa4710”) } 
{ “_id” : 1, “name” : “zmkzmkzmkzmkzmk” } 
{ “_id” : 2, “name” : “zmkzmkzmkzmkzmk” } 
{ “_id” : 3, “name” : “zmkzmkzmkzmkzmk” } 
{ “_id” : ObjectId(“566004d173c8340448fa4712”), “name” : “zmk” }

mongos> db.blog.find({},{“name”:1,”_id”:0}) 
{ “name” : “zmkzmkzmkzmkzmk” } 
{ “name” : “zmkzmkzmkzmkzmk” } 
{ “name” : “zmkzmkzmkzmkzmk” } 
{ “name” : “zmk” }

"$lt"、"$lte"、“$gt”，“$gte” 分别对应 <,<=，>,>=。

mongos> var insertName=function(){ 
… for(var i=0;i<10;i++){ 
… db.blog.insert({“_id”:1,”name”:”zmk”+i}) 
… } 
… } 
mongos> insertName() 

mongos> db.blog.find() 
{ “_id” : 1, “name” : “zmk0” } 
{ “_id” : 0, “name” : “zmk0” } 
{ “_id” : 2, “name” : “zmk2” } 
{ “_id” : 3, “name” : “zmk3” } 
{ “_id” : 4, “name” : “zmk4” } 
{ “_id” : 5, “name” : “zmk5” } 
{ “_id” : 6, “name” : “zmk6” } 
{ “_id” : 7, “name” : “zmk7” } 
{ “_id” : 8, “name” : “zmk8” } 
{ “_id” : 9, “name” : “zmk9” }

mongos> db.blog.insert({“_id”:10,”time”:new Date()}) 
WriteResult({ “nInserted” : 1 }) 
mongos> db.blog.find({“time”:{“$lt”:new Date()}}) 
{ “_id” : 10, “time” : ISODate(“2015-12-05T12:08:53.469Z”) }

mongos> db.blog.insert({“_id”:1,”fruit”:[“apple”,”banana”,”peach”]}) 
WriteResult({ “nInserted” : 1 }) 
mongos> db.blog.insert({“_id”:2,”fruit”:[“apple”,”kumquat”,”orange”]}) 
WriteResult({ “nInserted” : 1 }) 
mongos> db.blog.insert({“_id”:3,”fruit”:[“cherry”,”banana”,”apple”]}) 
WriteResult({ “nInserted” : 1 }) 
mongos> db.blog.find({“fruit”:{$all:[“apple”,”banana”]}}) 
{ “_id” : 1, “fruit” : [ “apple”, “banana”, “peach” ] } 
{ “_id” : 3, “fruit” : [ “cherry”, “banana”, “apple” ] }

mongos> db.blog.find({“fruit.2”:”peach”}) 
{ “_id” : 1, “fruit” : [ “apple”, “banana”, “peach” ] }

mongos> db.blog.find({“fruit”:{$size:3}}) 
{ “_id” : 1, “fruit” : [ “apple”, “banana”, “peach” ] } 
{ “_id” : 2, “fruit” : [ “apple”, “kumquat”, “orange” ] } 
{ “_id” : 3, “fruit” : [ “cherry”, “banana”, “apple” ] }

mongos> db.blog.find({“fruit”:{size:3}},{"fruit":{"slice”:-2}}) 
{ “_id” : 2, “fruit” : [ “kumquat”, “orange” ] } 
{ “_id” : 3, “fruit” : [ “banana”, “apple” ] }

mongos>db.people.find({“name.first”:”Joe”,”name.last”:”Schmoe”})

db.blog.find({“comments”:{“$elemMatch”:

{“author”:”joe”,”score”:{“$gte”:5}}}})

db.stock.find({“des”:”mp3”}).limit(50).sort({“price”:-1}) 
db.stock.find({“des”:”mp3”}).skip(50).limit(50).sort({“price”:-1}) 
……

var page1=db.stock.find({“des”:”mp3”}).limit(50).sort({“price”:-1}) 
var lastest=null;//解决方法，将游标最后一个文档记录下来，成为第二次查询的条件的一部分 
while(page1.hasNext()){ 
lastest=page1.next(); 
display(lastest); 
} 
var page2=db.stock.find({“des”:”mp3”},{“price”:{$gt:lastest.price}}).limit(50).sort({“price”:-1}) 
……