1代开一个cmd窗口，当作mongodb客户端，执行以下命令：
mongo localhost:27017
2查看所有的数据库：
> show dbs;
admin (empty)
local 0.078gb
3 db命令，查看当前窗口在那个数据库下面（test数据库没有任何数据，在内存里面）：
4创建集合
a 显示创建
db.createcollection(“collectionname”);
> db.createcollection("c1")
{ "ok" : 1 }
>
b 隐式创建
> db.c2.insert({name:"zhangsan",age:31})
writeresult({ "ninserted" : 1 });
显示集合
show collections;
5 crud
a添加
db.collectionname.insert({})
writeresult({ "ninserted" : 1 })
> show collections;
c1
c2
system.indexes
> var i = 1+2;
> i
3
> for(var i = 1 ; i <= 10000;i++){
... db.c1.insert({name:'toto',age:24})
... }
清屏命令：cls
b删除
db.collectionname.remove();
> db.c4.insert({name:"zhangsan",age:20});
> db.c4.insert({name:"lisi",age:24});
db.c4.find();
> db.c4.remove({name:"zhangsan"});
writeresult({ "nremoved" : 1 })
> db.c4.find();
{ "_id" : objectid("543e0b6ae2c90313035e7ce3"), "name" : "lisi", "age" : 24 }
c查询
a db.collectionname.find({条件});
eg：db.c3.find();
再如：
> db.c4.find({name:"lisi"});
b查找集合中的第一条数据
db.collectionname.findone();
eg：
{ "_id" : objectid("543e0d96e2c90313035e7ce4"), "name" : "wangwu", "age" : 20 }
{ "_id" : objectid("543e0da0e2c90313035e7ce5"), "name" : "zhaoliu", "age" : 25 }
{ "_id" : objectid("543e0da8e2c90313035e7ce6"), "name" : "tianqi", "age" : 25 }
> db.c4.findone();
{
"_id" : objectid("543e0b6ae2c90313035e7ce3"),
"name" : "lisi",
"age" : 24
}
注意：_id每个表都有，是mongodb自动维护的。
c查询集合中的文档，返回某些特定的键值
除了查询表达式以外，mongodb还支持一些额外的参数选项，例如，我们可能仅仅只想返回某些特定的字段值：
> db.c4.find({name:"wangwu"},{name:1});
{ "_id" : objectid("543e0d96e2c90313035e7ce4"), "name" : "wangwu" }
d查询显示问题
> for(var i = 1; i<=30;i++){
... db.c4.insert({name:"tuzuoquan",age:i});
查询：
{ "_id" : objectid("543e104fe2c90313035e7ce7"), "name" : "tuzuoquan", "age" : 1 }
{ "_id" : objectid("543e104fe2c90313035e7ce8"), "name" : "tuzuoquan", "age" : 2 }
{ "_id" : objectid("543e104fe2c90313035e7ce9"), "name" : "tuzuoquan", "age" : 3 }
{ "_id" : objectid("543e104fe2c90313035e7cea"), "name" : "tuzuoquan", "age" : 4 }
{ "_id" : objectid("543e104fe2c90313035e7ceb"), "name" : "tuzuoquan", "age" : 5 }
{ "_id" : objectid("543e104fe2c90313035e7cec"), "name" : "tuzuoquan", "age" : 6 }
{ "_id" : objectid("543e104fe2c90313035e7ced"), "name" : "tuzuoquan", "age" : 7 }
{ "_id" : objectid("543e104fe2c90313035e7cee"), "name" : "tuzuoquan", "age" : 8 }
{ "_id" : objectid("543e104fe2c90313035e7cef"), "name" : "tuzuoquan", "age" : 9 }
{ "_id" : objectid("543e104fe2c90313035e7cf0"), "name" : "tuzuoquan", "age" : 10 }
{ "_id" : objectid("543e104fe2c90313035e7cf1"), "name" : "tuzuoquan", "age" : 11 }
{ "_id" : objectid("543e104fe2c90313035e7cf2"), "name" : "tuzuoquan", "age" : 12 }
{ "_id" : objectid("543e104fe2c90313035e7cf3"), "name" : "tuzuoquan", "age" : 13 }
{ "_id" : objectid("543e104fe2c90313035e7cf4"), "name" : "tuzuoquan", "age" : 14 }
{ "_id" : objectid("543e104fe2c90313035e7cf5"), "name" : "tuzuoquan", "age" : 15 }
{ "_id" : objectid("543e104fe2c90313035e7cf6"), "name" : "tuzuoquan", "age" : 16 }
type "it" for more
> it
{ "_id" : objectid("543e104fe2c90313035e7cf7"), "name" : "tuzuoquan", "age" : 17 }
{ "_id" : objectid("543e104fe2c90313035e7cf8"), "name" : "tuzuoquan", "age" : 18 }
{ "_id" : objectid("543e104fe2c90313035e7cf9"), "name" : "tuzuoquan", "age" : 19 }
{ "_id" : objectid("543e104fe2c90313035e7cfa"), "name" : "tuzuoquan", "age" : 20 }
{ "_id" : objectid("543e104fe2c90313035e7cfb"), "name" : "tuzuoquan", "age" : 21 }
{ "_id" : objectid("543e104fe2c90313035e7cfc"), "name" : "tuzuoquan", "age" : 22 }
{ "_id" : objectid("543e104fe2c90313035e7cfd"), "name" : "tuzuoquan", "age" : 23 }
{ "_id" : objectid("543e104fe2c90313035e7cfe"), "name" : "tuzuoquan", "age" : 24 }
{ "_id" : objectid("543e104fe2c90313035e7cff"), "name" : "tuzuoquan", "age" : 25 }
{ "_id" : objectid("543e104fe2c90313035e7d00"), "name" : "tuzuoquan", "age" : 26 }
{ "_id" : objectid("543e104fe2c90313035e7d01"), "name" : "tuzuoquan", "age" : 27 }
{ "_id" : objectid("543e104fe2c90313035e7d02"), "name" : "tuzuoquan", "age" : 28 }
{ "_id" : objectid("543e104fe2c90313035e7d03"), "name" : "tuzuoquan", "age" : 29 }
{ "_id" : objectid("543e104fe2c90313035e7d04"), "name" : "tuzuoquan", "age" : 30 }
> db.c4.count();
34
>总结：
mongodb客户端默认一次显示20条记录
eg:显示age大于20个数据：
> db.c4.find({age:{$gt:20}});
eg:显示age >= 25的数据：
db.c4.find({age:{$gte:25}});
> db.c4.find({age:{$gte:25}});
eg:显示age <= 15的数据：
> db.c4.find({age:{$lte:15}});
eg:显示age不等于
2的数据：
> db.c4.find({age:{$ne:2}});
> db.c4.find().count();
> db.c4.find({age:{$ne:20}}).count();
32
> db.c4.find({age:{$ne:2}}).count();
33
e :分页
db.c4.find().skip(0).limit(10);
> db.c4.find().skip(0).limit(10);
eg：查询第