What are the common commands of MongoDB
What are the common commands of MongoDB? I believe many inexperienced people don't know what to do about it. Therefore, this article summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.
1. Database-related
1. Switch / create database
> use "dbname"
two。 Query all databases
> show dbs;mytest 0.000GB
3. View the database currently in use
> db.getName ()
Mytest
4. View database version
> db.version ()
4.2.8
5. View the link address of the current db
> db.getMongo ()
Connection to 127.0.0.1:27017
Second, user-related
1. Create an ordinary user (create a user cg with read and write permissions to the mytest database)
> db.createUser ({user: "cg", pwd: "lianshi", roles: [{role: "readWrite", db: "mytest"}]})
2. Delete user > db.dropUser ("yonghu")
3. Modify the user's password
Db.updateUser ("cg", {pwd: "123456"})
4. Enter data mytest, user name and password authentication
> db.auth ("cg", "lianshi"); third, set Collection correlation
1. Get data aggregation (table)
> db.getCollectionNames (); ["student"]
two。 Collection (table) insert data
Db.student.insert ({"id": "2", "name": "yxy"})
3. Query data
> db.student.find (); {"_ id": ObjectId ("5eef61f3447efbc4346fbb9b"), "id": "2", "name": "yxy"} {"_ id": ObjectId ("5eef61fe447efbc4346fbb9c"), "id": "1", "name": "hmf"} {"_ id": ObjectId ("5eeff9582e8cdcf5c32c0ecf"), "id": "3", "name": "yx"} is equivalent to: select* from student
4. Query unique field values
> db.student.distinct ("name"); ["hmf", "yx", "yxy"]
Will filter out the same data in name
Equivalent to: select distict name from student
5. Query the records of name = yxy
> db.student.find ({"name": "yxy"}); {"_ id": ObjectId ("5eef61f3447efbc4346fbb9b"), "id": "2", "name": "yxy"} {"_ id": ObjectId ("5ef077145c4ca32ccc787893"), "id": "2", "name": "yxy"}
Equivalent to: select * from student where name = "yxy"
6. Insert data of int32 field type
Db.student.insert ({"id": NumberInt (1234567), "name": "hu"})
7. Insert int64 field type data
Db.student.insert ({"age": NumberLong (22), "name": "hu"})
8. Insert Decimal field type data
Db.student.insert ({"va": NumberDecimal ("22.3"), "name": "hu"})
9. Query statement
Db.student.find ({}) .sort ({_ id:-1}) .limit (100)
10. Delete (collection) table
Db.student.drop (): after reading the above, have you mastered the common commands of MongoDB? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!
