MongoDB query command details, MongoDB command details

MongoDB query command details, MongoDB command details

1. query all records

Copy the Code as follows:

db.userInfo.find();

Equivalent:Select * from userInfo;

By default, 20 records are displayed on each page. If no record is displayed, you can use the it iteration command to query data on the next page. Note: Type It commandCannot contain ";"

However, you can set the size of data displayed on each page.DBQuery. shellBatchSize = 50;In this way, 50 records are displayed on each page.

2. query duplicate data of a column in the current clustering set after Removal

Copy the Code as follows:

db.userInfo.distinct("name");

The same data in name is filtered out.

Equivalent: Select distict name from userInfo;

3. query records with age = 22

Copy the Code as follows:

db.userInfo.find({"age": 22});

Equivalent:Select * from userInfo where age = 22;

4. query records of age> 22

Copy the Code as follows:

db.userInfo.find({age: {$gt: 22}});

Equivalent:Select * from userInfo where age> 22;

5. query records of age <22

Copy the Code as follows:

db.userInfo.find({age: {$lt: 22}});

Equivalent:Select * from userInfo where age <22;

6. query records with age> = 25
Copy the Code as follows:

db.userInfo.find({age: {$gte: 25}});

Equivalent:Select * from userInfo where age> = 25;

7. query records of age <= 25
Copy the Code as follows:

db.userInfo.find({age: {$lte: 25}});

8. query age> = 23 and age <= 26

Copy the Code as follows:

db.userInfo.find({age: {$gte: 23, $lte: 26}});

9. query data whose name contains mongo
Copy the Code as follows:

db.userInfo.find({name: /mongo/});

// Equivalent to %

Select * from userInfo where name like '% mongo % ';

10. query names starting with mongo
Copy the Code as follows:

db.userInfo.find({name: /^mongo/});

Select * from userInfo where name like 'mongo % ';

11. query the name and age data of a specified Column

Copy the Code as follows:

db.userInfo.find({}, {name: 1, age: 1});

Equivalent: Select name, age from userInfo;
Of course, "true" or "false" can be used for name. If "true" is used, "river name: 1" has the same effect. If "false" is used, "name" is excluded and column information other than "name" is displayed.

12. query the name and age data of a specified column. age> 25

Copy the Code as follows:

db.userInfo.find({age: {$gt: 25}}, {name: 1, age: 1});

Equivalent: Select name, age from userInfo where age> 25;

13. sort by age

Copy the Code as follows:

Ascending Order:

db.userInfo.find().sort({age: 1});

Descending order:

db.userInfo.find().sort({age: -1});

14. query data with name = zhangsan and age = 22
Copy the Code as follows:

db.userInfo.find({name: 'zhangsan', age: 22});

Equivalent: Select * from userInfo where name = 'hangsan' and age = '22 ';

15. query the first five data entries

Copy the Code as follows:

db.userInfo.find().limit(5);

Equivalent: Select top 5 * from userInfo;

16. Query 10 data records later

Copy the Code as follows:

db.userInfo.find().skip(10);

Equivalent:

Select * from userInfo where id not in (

Select top 10 * from userInfo
);

17. query data between 5-10

Copy the Code as follows:

db.userInfo.find().limit(10).skip(5);

Limit is the limit on the displayed quantity, and skip is the number of skipped.

18. or and query

Copy the Code as follows:

db.userInfo.find({$or: [{age: 22}, {age: 25}]});

Equivalent: Select * from userInfo where age = 22 or age = 25;

19. query the first data entry.

Copy the Code as follows:

db.userInfo.findOne();

Equivalent:

Select top 1 * from userInfo;

Db. userInfo. find (). limit (1 );

20. query the number of records in a result set
Copy the Code as follows:

db.userInfo.find({age: {$gte: 25}}).count();

Equivalent:Select count (*) from userInfo where age> = 20;

21. sort by Column
Copy the Code as follows:

db.userInfo.find({sex: {$exists: true}}).count();

Equivalent: Select count (sex) from userInfo;