MongoDB usage Record

Some MongoDB learning related knowledge, recorded so that the next time to view the use

Reference: https://docs.mongodb.com/manual/reference/operator/

Http://www.runoob.com/mongodb/mongodb-tutorial.html

Https://code.ziqiangxuetang.com/mongodb/mongodb-tutorial.html

1) Installation

Windows installation: Https://www.mongodb.com/download-center#community

Linux installation (Ubuntu): sudo apt-get install MongoDB

Windows environment, under the Server\3.6\bin\ directory under the installation directory there is a Mongo.exe, double-click to open

Linux environment, open the terminal input MONGO can

2) A brief description of MONGODB data structure

Combining MySQL data structure comparison

　　

　　

3) Data manipulation

View all databases: Show DBS

Create or switch a database: Use dbname (if the database exists then switch, do not exist to create)

Delete Current database:db. Dropdatabase()

View all tables in the database: show tables

All data operations in MongoDB use JavaScript syntax

1. Insert operation

First switch to a database, if not switch, the default in the test database operation

Of the two data, the data with ID 1, insert the operator as

Db.testable.insert ({   ' user_name ': ' Mark Hanks ',   ' email ': ' [email protected] ',   ' age ': +,   ' City ': ' Los Angeles '       })

The insert operation, if the testable table exists, inserts the data into the table, creates the table if it does not exist, and then inserts the data

MongoDB automatically creates field _id, type Object ID

Insert document You can also use the Db.testable.save command. If you do not specify the _id field, the Save () method is similar to the Insert () method. If the _id field is specified, the data for the _id is updated.

2. Query operations

For more detailed query operation, please refer to https://docs.mongodb.com/manual/reference/operator/query/

　　　　DB. Collection. Find(query, projection)

　　　　Query is the criteria for the search, projection uses the projection operator to specify the returned key, and ignoring the argument returns all keys

To query all the data in the collection:

Db.testable.find (). Pretty ()

The find () default parameter queries all data and appends the pretty () function to format the returned document data

For example, to query the data added above, the

Db.testable.find ({   ' name ': ' Mark Hanks '})

This operation queries the data for the last Name field, Mark Hanks

To query for data older than 20

Db.testable.find ({' Age   ': {' $gt ': 20}})

The above operation looks for data older than 20 GT corresponds to English greater than

The corresponding comparison symbols are:

$GT: Greater than (greater than)

$gte: Greater than or equal (greater than equal)

$LT: Smaller than (less than)

$lte: Less than or equal (than equal)

If you want to compare multiple times, you can separate them with commas, such as querying documents larger than 20 less than 25

Db.testable.find ({' Age   ': {' $gt ': $, ' $lt ': 25}})

You can also compare data types, such as querying the Name field for a string type of data

Db.testable.find ({'   name ': {' $type ': 2}})

2 is the type number of the string, and the corresponding code

The skip function and the limit function are useful if you want to implement how many data to skip and how many data to use.

For example, to skip the first 5 data and remove 5 data, then:

Db. Collection_name.find (). Limit (5). Skip (5)

Limit limits the number of bars to take out data, skip limits the number of skipped data

3. Delete operation

The basic syntax format for the Remove () method

Db.collection.remove (   <query>,   <justOne>)

The syntax format after MongoDB version 2.6

Db.collection.remove (   <query>,   {     justone: <boolean>,     Writeconcern: <document>   })

which

• • query : (optional) The condition of the deleted document.
  • justone : (optional) If set to TRUE or 1, only one document is deleted.
  • Writeconcern : (optional) the level at which an exception is thrown

For example, to delete the data inserted above, you can perform an action

Db.testable.remove ({   {' name ': ' Mark Hanks '},   {justone:true}})

This means deleting a data with the name Mark Hanks and, if Justone is false, deleting all data with the name Mark Hanks, which defaults to False

If you empty all the data in the collection, execute Db.testable.remove ({}) to

4) Update operation

The syntax format is as follows:

Db.collection.update (   <query>,   <update>,   {     upsert: <boolean>,     Multi: < Boolean>,     writeconcern: <document>   })

• • Query: The search condition for update, similar to where in SQL update query.
  • Update: Update object and some updated operators (such as $, $inc ... ) can also be understood as the SQL update query within the set after the
  • upsert : Optional, this parameter means that if there is no record of update, insert objnew,true as INSERT, default is False, do not insert.
  • multi : Optional, mongodb default is False, only update the first record found, if this parameter is true, will be found on the condition of a number of records update all.
  • writeconcern : Optional, throws an exception level.

For example, to set the age of the data user_name to mark Hanks to 30

Db.collection.update (   {' user_name ': ' Mark Hanks '},   {' $set ': {' age ': +}},   {     multi:true   })

For more detailed update operations please refer to https://docs.mongodb.com/manual/reference/operator/update/

MongoDB usage Record