Join the social network of Tech Nerds, increase skill rank, get work, manage projects...
 
  • Top MongoDB Commands

    • 0
    • 2
    • 1
    • 1
    • 0
    • 0
    • 0
    • 0
    • 718
    Comment on it

    Small But Very Useful And Frequently Used Commond

    Step1: Remove lock file.
    sudo rm /var/lib/mongodb/mongod.lock
    sudo rm-rf mongodb/mongod.lock

    Step2: Repair mongodb.
    mongod --repair

    Step3: Start mongodb.
    sudo mongod -dbpath=mongodb
    sudo start mongodb
    or
    sudo service mongodb start

    Step4: Check status of mongodb.
    sudo status mongodb
    or
    sudo service mongodb status

    Step5: Start mongo console.
    mongo

    Basic and Important MongoDB Commands

    1. Connect to a Database

      To connect to the database server, which runs as mongod, and begin using the mongo shell to select a logical database within the database instance and access the help text in the mongo shell.

      Commond : mongod

      Task Perform: Connect to DB.


    2. Show all DB

      Commond : show dbs

      Task Perform: Show all DB


    3. Create New DB

      Commond : use databaseName

      Task Perform: Create new DB


    4. Insert New Document

      Insert the j and k documents into the testData collection with the following sequence of operations:

      Commond : db.testData.insert( j )
      db.testData.insert( j )

      Task Perform: Insert new Document

    5. Find Data using mongoDB

      Confirm that the documents exist in the testData collectionModifies an existing document or documents in a collection. The method can modify specific fields of an existing document or documents or replace an existing document entirely, depending on the update perameter. By default, the update() method updates a single document. Set the Multi Parameter to update all documents that match the query criteria. by issuing a query on the collection using the find() method:

      Commond : db.testData.find()

      Task Perform : Find all the collection data


    6. Update Data using mongoDB

      Modifies an existing document or documents in a collection. The method can modify specific fields of an existing document or documents or replace an existing document entirely, depending on the update perameter.
      By default, the update() method updates a single document. Set the Multi Parameter to update all documents that match the query criteria.

      The update() method has the following form:

      Commond :
      db.collection.update( , , { upsert: , multi: , writeConcern: } )

      NOTE :

      upsert

      Optional. If set to true, creates a new document when no document matches the query criteria. The default value is false, which does not insert a new document when no match is found.

      multi

      Optional. If set to true, updates multiple documents that meet the query criteria. If set to false, updates one document. The default value is false.

      writeConcern

      Optional. A document expressing the write concern . Omit to use the default write concern.

      Example
      db.collection.update( { "_id.authorID": 1 },
                                             { "name": "Robert Frost" },
                                             { upsert: true }   
        )
      

      $setOnInsert

      Commond :

      db.collection.update(
             <query>,
             { $setOnInsert: { <field1>: <value1>, ... } },
             { upsert: true }
          )
      

      If upsert : true , then $setOnInsert assigns the specified values to the fields in the document. If the update operation does not result in an insert, $setOnInsert does nothing. We can specify the upsert option for either the db.collection.update( ) or db.collection.findAndModify() methods.



    7. $set

      If the field does not exist, $set will add a new field with the specified value.If there is same field then $set will modify it.

      Example

      Consider a collection products with the following document:

       {
            _id: 100,
            sku: "abc123",
            quantity: 250,
            instock: true,
            reorder: false,
            details: { model: "14Q2", make: "xyz" },
            tags: [ "apparel", "clothing" ],
            ratings: [ { by: "ijk", rating: 4 } ]
         }
          db.products.update(
             { _id: 100 },
               { $set:
                  {
                    quantity: 500,
                    details: { model: "14Q3", make: "xyz" },
                    tags: [ "coats", "outerwear", "clothing" ]         
                  }
               }
          )
      

      Here we can see we have product collection with same id and we have to modify our quantity, detail and tag field so by using $set we can perform such task.

    8. Delete Record using MangoDB

      Commond: db.collection.remove(,)

      Example:

      db.products.remove( { qty: { $gt: 20 } } )
      



      The following operation removes all the documents from the collection products where qty is greater than 20



    9. $Unset

      The $unset operator deletes a particular field. Consider the following syntax:

      Commond: { $unset: { : "", ... } }

      Example:

      db.products.update(
         { sku: "unknown" },
         { $unset: { quantity: "", instock: "" } }
      )
      

    Refrences

    http://docs.mongodb.org/manual/reference/method/db.collection.update
    http://docs.mongodb.org/v2.4/reference/method/db.collection.update/

 0 Comment(s)

Sign In
                           OR                           
                           OR                           
Register

Sign up using

                           OR                           
Forgot Password
Fill out the form below and instructions to reset your password will be emailed to you:
Reset Password
Fill out the form below and reset your password: