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In this paper, an example is given to illustrate the simple operation of CURD for getting started with mongodb database. Share with you for your reference, the details are as follows:

View all databases

Some versions of show dbs;show databases; # may not work

Using the database

Use database name

View the collection (the collection is the table of the mysql)

Show tables/collections

View help

Db.help ()

Create a library

The library of MongoDB is created implicitly and can use a library that does not exist.

Then you can create a library by creating a colletion under the library.

Delete database

Db.dropDatabase ()

Create a collection

Db.createCollection (name, options)

Example: > db.createCollection ('student')

Delete a collection

Db.collectionName.drop ()

Insert document (add data)

Db.COLLECTION_NAME.insert (document)

Example:

Db.student.insert ({name:'zhang san',age:10})

Delete document

Db.COLLECTION_NAME.remove (query expressions, options)

Example:

Db.student.remove ({'_ id':ObjectId ('5bc57f9e0a64e83e9db621ca')})

The second parameter:

JustOne: (optional) if set to true or 1, only one document is deleted, which is equivalent to limit 1.

Update document

Db.collectionName.update (, {upsert:, / / if not, add data multi:, writeConcern:})

Example:

Db.student.update ({'age':12}, {$set: {' name':'li si2'} $rename: {'birth':'birthday'} $inc: {' age':16}, $unset: {'status':1}})

Description:

If you do not use $set, the whole piece of data will be modified to new data.

After using $set, modify only the columns you want to modify.

$unset deletes a column $rename renames a column $inc increases the value of a column

Query document

Db.collection.find (query, projection)

Example:

Db.student.findOne (); / query a db.student.find (); / query all db.student.find ({}, {name:1}); / / query name column (including _ id) db.student.find ({}, {name:1,_id:0}); / / query name column (excluding _ id)

It is hoped that what is described in this article will be helpful to the programming of MongoDB database.

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