Basic operation of MongoDB

Querying all the Databases

Show DBS

Specify to a database/or create

Use database name

Specify storage size

Db.createcollection ("Mycoll", {capped:true,size 10000})

Inserting data

Db. Collection. Insert ({key:values})

Db. Collection. Save ({key:values})

Querying documents

Db. Collection. Find ()

Total query data

Db. Collection. Count ()

MongoDB Limit () method

If you need to read a specified number of data records in MongoDB, you can use the MongoDB limit method, and the limit () method accepts a numeric parameter that specifies the number of record bars read from MongoDB.

Specify the number of bars to read

Db. Set find (). limit (count);

Skips a specified number of rows

Db. Collection. Find (). Limit (count). Skip (count) skip defaults to 0

Sort () method ordering

Parameters are two 1 or-1, ascending or descending

Db. Set find (). Sort ()

Deleting a database

Use database

Dorp. Database ()

Delete Collection

Db.collection.drop ();

Querying database Collections

Db. Collection. Find ()

Update document

Update ()

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db.collection. update ( &NBSP;&NBSP;&NBSP; < Query>, &NBSP;&NBSP;&NBSP; < update >,      { &NBSP;&NBSP;&NBSP;&NBSP;&NBSP; Code class= "SQL Plain" >upsert: <boolean>,       multi: <boolean>,        writeconcern: <document>      } )

　

Parameter description:

• 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.

Example

Db. Collection. Update ({Query condition}, ($set: {Modify content}))

If you want to modify more than one document

Db. Collection. Update ({Query condition}, ($set: {Modify content}), {multi:true})

Eg:db.mylog.update ({"Name": "Zhangsan"}, {$set: {"test": "Test1"}})

Delete a document

Db. Collection. Remove (delete condition)

Delete the first data found

Db. Collection. Remove (delete condition)

Delete all

Db. Collection. Remove ({})

Multi-Key Query

Eg:db. Collection. Find ({key:values,key:values}). Pretty ()//equivalent to the Where condition one and condition two in SQL

Or

Db. Collection. Find (

{

$or [{key:values},

{Key:values}

]

}

). Pretty ()

With AND and OR

Db. Collection. Find ({key:values}, $or [{condition two},{or condition two}]. Pretty ()

MongoDB Index

Db. Collection. Ensureindex ({indexed by what})

Eg:db.numbers.ensureIndex ({num:1})

Explain usage:

Eg:db.numbers.find ({num:{"$gt": 19995}}). explain

Ext.: http://www.cnblogs.com/tsxylhs/p/5657298.html

Basic operation of MongoDB