最近在自学MongoDB，
连接数据库
mongo.exe test
设置访问限制后连接
mongo.exe -u root -p test
设置访问限制
db.addUser("root","111111");
mongo.exe auth;
创建集合(数据库)
db.createCollection("mydatabase",{size:1000000,max:100});
切换数据库
use mydatabase;
创建表(student)
db.student.save({_id:1,classid:1,age:18,name:"little1",love:["football","swing","cmpgame"]});
db.student.save({_id:2,classid:2,age:19,name:"little2",love:["play"]});
db.student.save({_id:3,classid:2,age:20,name:"little3"});
db.student.save({_id:4,classid:1,age:21,name:"little4"});
db.student.save({_id:5,classid:1,age:22,name:"little5",opt:"woshisheia"});
db.student.save({_id:6,classid:2,age:23,name:"23little4"});
查询:
db.student.find();
//从第二条查寻，查出三条
db.student.find().skip(1).limit(3);
//查询出name为little1的数据
db.student.find({name:"little1"});
//查询出19<age<=21的数据
db.student.find({age:{$gt:19,$lte:21}});
//$mod:查询出age为奇数的数据(对2求余为1即为奇数)(这里请注意[2,1]的位置不能错)
db.student.find({age:{$mod:[2,1]}});
//$exists：查询出存在opt字段的数据, 存在true，不存在false
db.student.find({opt:{$exists:true}}); db.student.find({opt:{$exists:false}});
//查询出name不为little2的数据
db.student.find({name:{$ne:"little2"}});
//$in:查询出age为16，18，19的数据
db.student.find({age:{$in:[16,18,19]}});
//$nin:查询出age不为16，18，19的数据
db.student.find({age:{$nin:[16,18,19]}});
//$size:查询出love有三个的数据
db.student.find({love:{$size:3}});
//查询出name不是以litt开头的数据
db.student.find({name:{$not:/^litt.*/}});
//查询age>20的数据
db.student.find({age:{$gt:20}});
db.student.find({$where:"this.age>20"});
db.student.find("this.age>20");
var f = function(){return this.age>20};
db.student.find(f);
//sort：1升序， -1降序
按age升序：db.student.find().sort({age:1}); 按age降序：db.student.find().sort({age:-1});
//count：查询数据条数
db.student.find().count();
//like：模糊查询
db.student.find({name:/little/}); 相当于 select * from student where name like "%little%";
db.student.find({name:/^little/}); 相当于 select * from users where name like "little%";
//distinct：去重
db.student.distinct('name');
//type：属性类型判断
db.sutdent.find({"title" : {$type : 2}}) db.student.find({"title" : {$type : 'string'}})
//查询 name为little1的学生，并且只显示 age,name两个字段
db.student.find({name:"little1"},{name:1,age:1}) 等价于 select name,age from student where name = "little1"
//and：查询 name为little1,age为18的学生，并且只显示 age,name,love三个字段
db.student.find({name:"little1",age:18},{name:1,age:1,love:1}) 等价于 select name,age,love from student where name = "little1" and age = 18
//or：查询 name为little3或age为19的学生
db.student.find({'$or':[{name:'little3'},{age:19}]}) 等价于 select * from student where name = "little3" or age = 19
//null：查询age为null的数据
db.student.find({age:null})
//
删除:
//删除age为20的数据
db.student.remove({age:20});
//删除表
db.student.drop();
存储过程:
db.system.js.save({_id:"mypro",value:function(){
var total = 0;
var arr = db.student.find().toArray();
for(var i=arr.length-1;i>=0;i--){
total += arr[i].age;
}
return total;
}});
//查询存储过程
db.system.js.find();
//执行存储过程
db.eval("mypro()");
分组统计(MapReduce):
var mapfun = function(){emit(this.classid,1)}
var reducefun = function(key, values){
var x = 0;
values.forEach(function(v){x+=v});
return x;
}
var finafun = function(key, value){
return {classid:key,count:value};
}
res = db.runCommand({
mapreduce:"student",
map:mapfun,
reduce:reducefun,
out:student_res,
finalize:finafun
//可加入条件
//query:{age:{$gt:19}}
});
//查询统计结果(分班级统计人数)
db.student_res.find();