Java--mongoDB

mongo==> enter
use xxx ==> select database
db ==> View the currently connected database
show dbs ==> view all databases
db.dropDatabase() ==> destroy the database
 
db.createCollection( "xxx")==> Create a collection
show collections ==> view all collections
db.xxx.deop() ==> delete collection
db.xxx.insert([{name: "",},{name:""}])==> Insert data into the collection
db.xxx.update([{}]) ==> update collection data
db.xxx.remove([{}]) ==> delete collection data
db.xxx.find() ==> query
db.xxx.find().pretty ==> query results are more beautiful

db.post.find({
    $or:[
        {"by":"shiyanlou"},
        {"title": "MongoDB Overview"}
    ]
}).pretty()

==>or usage

 

Conditional operator 1:

(>) greater than - $gt #greater than

(<) less than - $lt #less than

(>=) greater than or equal to - $gte #equal

(<= ) less than or equal to - $lte

Conditional operator 2:

type

 

 

 

 

 

example:

1. Look at the sql statement of the window and write down the returned sql parameters

2. Write down the method

 

3. Test sql in mongodb

 

4. There is a problem that the index cannot be empty in mongodb. Under the Maven command for multiple updates, the data corresponding to the local Maven cannot be deleted and then updated.

There is a problem that the index cannot be empty in mongodb. It cannot be deleted and updated under the Maven command for multiple updates.

 Replenish:

In the mongoDB database, the time is saved in the ISODate type, and the orm relationship is mapped to the java.util.Date type. The time saved is 8 hours different from ours (the time saved is 8 hours earlier than us).