MongoDB常用操作

一、查询
find方法
db.collection_name.find();
查询所有的结果:
select * from users;
db.users.find();

指定返回那些列(键):
select name, skills from users;

db.users.find({}, {‘name’ : 1, ‘skills’ : 1});
补充说明: 第一个{} 放where条件 第二个{} 指定那些列显示和不显示 (0表示不显示 1表示显示)

where条件:

1.简单的等于:
select name, age, skills from users where name = ‘hurry’;
db.users.find({‘name’ : ‘hurry’},{‘name’ : 1, ‘age’ : 1, ‘skills’ : 1});

2.使用and
select name, age, skills from users where name = ‘hurry’ and age = 18;
db.users.find({‘name’ : ‘hurry’, ‘age’ : 18},{‘name’ : 1, ‘age’ : 1, ‘skills’ : 1});

3.使用or
select name, age, skills from users where name = ‘hurry’ or age = 18;
db.users.find({ ‘$or’ : [{‘name’ : ‘hurry’}, {‘age’ : 18}] },{‘name’ : 1, ‘age’ : 1, ‘skills’ : 1});

4.<, <=, >, >= (lt,lt,lte, gt,gt,gte )
select * from users where age >= 20 and age <= 30;
db.users.find({‘age’ : {‘gte′:20,′gte′:20,′lte’ : 30}});

5.使用in, not in (in,in,nin)
select * from users where age in (10, 22, 26);
db.users.find({‘age’ : {‘$in’ : [10, 22, 26]}});

6.匹配null
select * from users where age is null;
db.users.find({‘age’ : null);

7.like (mongoDB 支持正则表达式)
select * from users where name like “%hurry%”;
db.users.find({name:/hurry/});
select * from users where name like “hurry%”;
db.users.find({name:/^hurry/});

8.使用distinct
select distinct (name) from users;
db.users.distinct(‘name’);

9.使用count
select count(*) from users;
dunt();

10.数组查询 (mongoDB自己特有的)
如果skills是 [‘java’,’python’]
db.users.find({‘skills’ : ‘java’}); 该语句可以匹配成功
alldb.users.find(‘skills′:‘$all′:[‘java′,′python′])skills中必须同时包含java和pythonalldb.users.find(‘skills′:‘$all′:[‘java′,′python′])skills中必须同时包含java和pythonsize
db.users.find({‘skills’ : {‘size' : 2}}) 遗憾的是size' : 2}}) 遗憾的是size不能与lt等组合使用lt等组合使用slice
db.users.find({‘skills’ : {‘$slice : [1,1]}})
两个参数分别是偏移量和返回的数量
 

posted on 2019-06-13 23:24  aspsea  阅读(129)  评论(0编辑  收藏  举报