MongoDB shell operations

The shell command operation syntax is similar to that of JavaScript. In fact, the underlying query statements on the console are all completed using JavaScript scripts. Run the shell command to start cmd.exe.

Common shell commands are as follows:

1. query the names of all local databases

> show dbs;

2. Switch to the specified database environment (if no database is specified, a new database is created)

> use mydb;

3. query all collection sets in the current database (equivalent to table)

> show collections;

4. Create a collection

> db.createCollection('mycollection');

5. query the number of data entries in the aggregation set

> db.mycollection.count();

6. insert data

> db.mycollection.insert({'username':'xyz_lmn','age':26,'salary':120});

Insert a number Library to the 'mycollection' collection. The name is 'xyz _ lmn ', the age is '26', and the salary is '123'

7. query data with age equal to 26

> db.mycollection.find({"age":26});

8. query data with salary greater than 100

> db.mycollection.find({salary:{$gt:100}});

9. query data with age less than 30 and salary greater than 100

> db.mycollection.find({age:{$lt:30}},{salary:{$gt:100}});

10. query data with salary less than 40 or salary greater than 200

> db.mycollection.find({$or: [{salary: {$lt:40}}, {salary: {$gt:200}}]});

11. query the data of a specified Column

> db.mycollection.find({},{age:1,salary:1});

1 indicates the meaning of the column, or true.
12. query data whose username contains 'E'

> db.mycollection.find({username:/e/});

13. query data headers with a header

> db.mycollection.find({username:/^a/});

14. query age column data and remove duplicate data

> db.mycollection.distinct('age');

15. query the first 10 data records

> db.mycollection.find().limit(10);

16. query all data after one record

> db.mycollection.find().skip(1);

17. query the first data entry.

> db.mycollection.findOne();

18. Number of records in the query result set (number of records whose salary is less than 40 or greater than 100)

db.mycollection.find({$or: [{salary: {$lt:40}}, {salary: {$gt:100}}]}).count();

19. sort by salary in ascending order

> db.mycollection.find().sort({salary:1});

Sort by salary field in ascending order

20. Descending Order

> db.mycollection.find().sort({salary:-1});

Sort by salary field in descending order

21. Modify the age according to Username

> db.employee.update({username:'jim'},{$set:{age:22}},false,true);

DB. collection. Update (criteria, objnew, upsert, multi)

Criteria: Query condition for update, similar to
Objnew: The update object and some updated operators (such as $, $ Inc...) can also be understood as
Upsert: If no update record exists, whether to insert objnew. True indicates insertion. The default value is false.
Multi: the default value of mongodb is false. Only the first record found is updated. If this parameter is set to true, all the records identified by the condition are updated.

22. Add the age field of the specified username to 5

> db.mycollection.update({username:'jim'},{$inc:{age:5}},false,true);

Add the age field with username 'Jim 'to 5
23. delete data whose username is 'Rose'

> db.mycollection.remove({uname:'rose'});

24. Rename collection

> db.mycollection.renameCollection('c_temp');

Rename the mycollection set to 'C _ temp'

25. delete a set

> db.c_temp.drop();

Delete A set named 'C _ temp'

26. Delete the current database

> db.dropDatabase();