{% endhighlight %}

3. 查询命令

值精确匹配的查询

db.students.find({name: "张三"})

两个条件（逻辑与）

db.students.find({name: /^小/})

db.students.find({name: /.*四/})

3. Update命令

暂无

6. 内嵌数组查询

db.students.insert({name: "张三", school: {name: "清华大学", city: "北京"}, courses:[{name:"MongoDB", grade:88, quiz:[9,8,9,10]},{name:"Java", grade:99,quiz:[3,2,1,5]}], age: 19, gpa: 3.97})

db.students.insert({name: "李四", school: {name: "北京大学", city: "北京"}, courses:[{name:"MongoDB", grade:86, quiz:[5,4,3,7]},{name:"Java", grade:92}, {name:"C++", grade:65}], age: 20, gpa: 3.3})

db.students.insert({name: "小马", school: {name: "交通大学", city: "西安"}, courses:[{name:"MongoDB", grade:96, quiz:[5,4,3,7]}], age: 21, gpa: 3.70})

db.students.insert({name: "小朱"})

7. 地理位置查询

db.pois.insert({name:"AAA Store", loc:{type:"Point", coordinates:[70,30]}})

db.pois.insert({name:"BBB Bank", loc:{type:"Point", coordinates:[69.99,30.01]}})

db.pois.insert({name:"CCC Park", loc:{type:"Polygon", coordinates:[[[70,30],[71,31],[71,30],[70,30]]]}})

maxDistance: 7000

}

)

9. 全文搜索

db.text.insert({content:"text performs a text search on the content of the fields indexed with a text index."})

db.text.insert({content:"When dealing with a small number of documents, it is possible for the full-text-search engine to directly scan the contents of the documents with each query, a strategy called 'serial scanning.' This is what some rudimentary tools, such as grep, do when searching."})

db.text.insert({content:"Soros enjoys playing mongo."})

db.text.insert({content:"Why don't you use mongo-db?"})

10. 学生成绩Group命令

db.students.group({

key:{age:1},

cond: {age:{$exists:true}},

reduce:function(cur, result) { result.count += 1; result.total_gpa += cur.gpa; result.ava_gpa = result.total_gpa / result.count;},

initial: { count: 0 , total_gpa: 0}

})

11. 数据聚合 -- 流水线

各年龄段平均GPA计算和排序

db.students.aggregate([

{$match:{age:{$exists:true}}},

{$group:{_id:"$age", count: {$sum:1}, total_gpa:{$sum:"$gpa"}}},

{$sort: {cc:-1}}

]

)

12 数据聚合MapReduce

按age分组计算平均gpa (错误)

db.students.mapReduce(

function(){

])

.highlight .nn { color: #93A1A1 }

.highlight .py { color: #93A1A1 }