Skip to main content

Update document - MongoDB

To update document of MongoDB collection we can use update() and save() methods.

1- update() method replace the existing value of existing document in MongoDB collection.

2- save() method replace the existing document with passed document in MongoDB collection.

MongoDB Update() method
When we want to update existing value of document then we have to use update() method.

SYNTAX:
Basic syntax of update() method is given below:


>db.COLLECTION_NAME.update(SELECTIOIN_CRITERIA, UPDATED_DATA)


EXAMPLE:
Below is existing data in collection.


{ "_id" : ObjectId(5983548781331adf45ec5), "title":"MongoDB Overview", "by":"codefari.com"}
{ "_id" : ObjectId(5983548781331adf45ec6), "title":"ASP.Net Over view", "by":"codefari.com"}
{ "_id" : ObjectId(5983548781331adf45ec7), "title":"SQL Server 2014", "by":"codefari.com"}


Below given example will set the new title 'New MongoDB overview by  dilip' with existing title 'MongoDB Overview'


>db.mycol.update({'title':'MongoDB Overview'},{$set:{'title':'MongoDB overview and documentation'}})




>db.mycol.find()

{ "_id" : ObjectId(5983548781331adf45ec5), "title":" MongoDB overview and documentation", "by":"codefari.com"}
{ "_id" : ObjectId(5983548781331adf45ec6), "title":"ASP.Net Over view", "by":"codefari.com"}
{ "_id" : ObjectId(5983548781331adf45ec7), "title":"SQL Server 2014", "by":"codefari.com"}
> 


To update multiple we need to set a parameter 'multi' to true because by default MongoDB collection will update only single document.

>db.mycol.update({'title':'MongoDB Overview'},{$set:{'title':' MongoDB overview and documentation '}},{multi:true})


MongoDB Save() Method
Replaces the existing document with the new document passed in save () method.

SYNTAX:
Below is given basic syntax of MongoDB Collection save() method:


>db.COLLECTION_NAME.save({_id:ObjectId(),NEW_DATA})



EXAMPLE:
Following example will replace the document with the _id '5983548781331adf45ec7'


>db.mycol.save(
   {
      "_id" : ObjectId(5983548781331adf45ec7), "title":"MongoDB with elastic search"
   }
)



>db.mycol.find()

{ "_id" : ObjectId(5983548781331adf45ec5), "title":" MongoDB with elastic search "}
{ "_id" : ObjectId(5983548781331adf45ec6), "title":"ASP.Net Over view", "by":"codefari.com"}
{ "_id" : ObjectId(5983548781331adf45ec7), "title":"SQL Server 2014", "by":"codefari.com"}
> 

Popular posts from this blog

What is difference between UNION and UNION ALL in SQL Server

We use UNION and UNION ALL operator to combine multiple results set into one result set.
UNION operator is used to combining multiple results set into one result set but removes any duplicate rows. Basically, UNION is used to performing a DISTINCT operation across all columns in the result set. UNION operator has the extra overhead of removing duplicate rows and sorting result.
UNION ALL operator use to combine multiple results set into one result set but it does not remove any duplicate result. Actually, this does not remove duplicate rows so it is faster than the UNION operator. If you want to combine multiple results and without duplicate records then use UNION otherwise UNION ALL is better.
Following some rules for using UNION/UNION ALL operator
1.The number of the column should be the same in the query's when you want to combine them. 2.The column should be of the same data type. 3.ORDER BY clause can be applied to the overall result set not within each result set.
4.Column name of …

Merge and Merge join transformation in SSIS

MERGE TRANSFORMATION
Using Merge Transformation we can combine two sorted data-set into single data-set basically Merge Transformation used to combines rows from two sorted data flows into one sorted data flow. Following tasks you may perform using Merge Transformation: 1.Suppose we have a scenario like, we need to merge data from a database table and excel means we want to merge data from two different data sources. For such type of scenario, you can use Merge Transformation. 2.If we want to merge data from two same structured tables but exists two different servers. 3.Sometimes we get an error due to data in a row, after correcting errors in the data we can re-merge rows easily. See below explanations may help you to understand Merge Transformation: I do evaluate here, you already know about the data source, data conversion, data flow, task flow, control flow etc. Note:Before Merge transformation, we need to sort the data using Sort Transformation. After sorting data add data path to Merge…

Add day to ISODate in MongoDB

We can use $add operator to add days in ISODate in mongodb, $add is the Arithmetic Aggregation Operator which adds number and date in mongodb.
Syntax:

{ $add: [ <expression1>, <expression2>, ... ] }

Note:  If one of the argument is date $add operator treats to other arguments as milliseconds to add to the date.
Example: Suppose we have a Test collection as below.

{"Title" : "Add day to ISODate in MongoBD","CreatedDate" : ISODate("2016-07-07T08:00:00.000Z")}

Query to add 2 days in CreatedDate

db.Test.aggregate([      { $project: { Title: 1, AddedDate: { $add: [ "$CreatedDate", 2*24*60*60000 ] } } }    ])

Result:

{ "_id" : ObjectId("579a1567ac1b3f3732483de0"), "Title" : "Add day to ISODate in MongoBD", "AddedDate" : ISODate("2016-07-09T08:00:00.000Z") }

Note: As mentioned in above note we have to convert days in millisecond because $add operator treat to other arg…