Skip to main content

Updating Collection in MongoDB

We can use update() method to update a collection in MongoDB.

Basic syntax will be like this:

db.<Collection Name>.update().

To update() method, we need to pass the data selection criteria and what we need to update in the selected data.

I have a below collection and data.



I want to update student name who is having ID 100 in the above collection. To do this, I have to execute below query.



We can upsert data as well into collection (Upsert definition: If data exists for the selection criteria then data will be updated otherwise, data will be inserted as new document into collection)
To upsert data, we need to pass "upsert":true option to the update() method.
In the below example, i am trying to upsert record with Student Id 102. But this 102 does not exist so it should insert as new record.



update() will update only first record by default. To update multiple records, we need to pass "true" value for "multi" key in update query.

Let's assume i have multiple records with the Student ID 105. I want to update all the records. This query will do that.



In the above data, the status is "active" for the records with ID 105. Now, am going to update those with "Inactive" using below query.



Here, $set used to set the value for only the mentioned field.

Comments

Post a Comment

Popular posts from this blog

Comparing Objects in Informatica

We might face a scenario where there may be difference between PRODUCTION v/s SIT version of code or any environment or between different folders in same environment. In here we go for comparison of objects we can compare between mappings,sessions,workflows In Designer it would be present under "Mappings" tab we can find "Compare" option. In workflow manger under "Tasks & Workfows" tab we can find "Compare" option for tasks and workflows comparison respectively. However the easiest and probably the best practice would be by doing using Repository Manager.In Repository Manager under "Edit" tab we can find "Compare" option. The advantage of using Repository manager it compares all the objects at one go i.e. workflow,session and mapping. Hence reducing the effort of individually checking the mapping and session separately. Once we select the folder and corresponding workflow we Can click compare for checking out

Finding Duplicate records and Deleting Duplicate records in TERADATA

Requirement: Finding duplicates and removing duplicate records by retaining original record in TERADATA Suppose I am working in an office and My boss told me to enter the details of a person who entered in to office. I have below table structure. Create Table DUP_EXAMPLE ( PERSON_NAME VARCHAR2(50), PERSON_AGE INTEGER, ADDRS VARCHAR2(150), PURPOSE VARCHAR2(250), ENTERED_DATE DATE ) If a person enters more than once then I have to insert his details more than once. First time, I inserted below records. INSERT INTO DUP_EXAMPLE VALUES('Krishna reddy','25','BANGALORE','GENERAL',TO_DATE('01-JAN-2014','DD-MON-YYYY')) INSERT INTO DUP_EXAMPLE VALUES('Anirudh Allika','25','HYDERABAD','GENERAL',TO_DATE('01-JAN-2014','DD-MON-YYYY')) INSERT INTO DUP_EXAMPLE VALUES('Ashok Vunnam','25','CHENNAI','INTERVIEW',TO_DATE('01-JAN-2014',

Target Load Type - Normal or Bulk in Session Properties

We can see the Target load type ( Normal or Bulk) property in session under Mapping tab and we will go for Bulk to improve the performance of session to load large amount of data. SQL loader utility will be used for Bulk load and it will not create any database logs(redolog and undolog), it directly writes to data file.Transaction can not be rolled back as we don't have database logs.However,Bulk loading is very as compared to Normal loading. In target if you are using Primary Key or Primary Index or any constraints you can't use Bulk mode. We can see this property in the below snap shot.