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- MongoDB - Data Types
- MongoDB - Insert Document
- MongoDB - Query Document
- MongoDB - Update Document
- MongoDB - Delete Document
- MongoDB - Projection
- MongoDB - Limiting Records
- MongoDB - Sorting Records
- MongoDB - Indexing
- MongoDB - Aggregation
- MongoDB - Replication
- MongoDB - Sharding
- MongoDB - Create Backup
- MongoDB - Deployment
MongoDB - Java
- MongoDB - Java Setup
- MongoDB - Java - Create Collection
- MongoDB - Java - Get Collection
- MongoDB - Java - Insert Document
- MongoDB - Java - Retrieve Documents
- MongoDB - Java - Update Document
- MongoDB - Java - Delete Document
- MongoDB - Java - Drop Collection
- MongoDB - Java - List Collections
MongoDB - PHP
- MongoDB - PHP Setup
- MongoDB - PHP - Create Collection
- MongoDB - PHP - Get Collection
- MongoDB - PHP - Insert Document
- MongoDB - PHP - Retrieve Documents
- MongoDB - PHP - Update Document
- MongoDB - PHP - Delete Document
- MongoDB - PHP - Drop Collection
- MongoDB - PHP - List Collections
MongoDB - Advanced
- MongoDB - Relationships
- MongoDB - Database References
- MongoDB - Covered Queries
- MongoDB - Analyzing Queries
- MongoDB - Atomic Operations
- MongoDB - Advanced Indexing
- MongoDB - Indexing Limitations
- MongoDB - ObjectId
- MongoDB - Map Reduce
- MongoDB - Text Search
- MongoDB - Regular Expression
- Working with Rockmongo
- MongoDB - GridFS
- MongoDB - Capped Collections
- Auto-Increment Sequence
MongoDB - Useful Resources
MongoDB Online Quiz
Following quiz provides Multiple Choice Questions (MCQs) related to MongoDB Framework. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz.
Q 1 - In a collection that contains 100 post documents, what does the following command do?
db.posts.find().skip(5).limit(5)
A - Skip and limit nullify each other. Hence returning the first five documents.
B - Skips the first five documents and returns the sixth document five times
C - Skips the first five documents and returns the next five
D - Limits the first five documents and then return them in reverse order
Answer : C
Explanation
The skip and limit functions are applies linearly and hence it will first skip documents 1-5, and then return documents 6-10.
Q 2 - Which of the following commands finds all the documents in the posts collection with post timestamp field as null?
A - db.posts.find( { post_timestamp : { $type: 10 } } )
B - db.posts.find( { post_timestamp: { $type: null } } )
C - db.posts.find( { post_timestamp: { $fieldtype: 10 } } )
D - db.posts.find( { post_timestamp: { $fieldtype: null } } )
Answer : A
Explanation
$type is used for all the operations involving checking the type of a field in MongoDB. 10 represents the BSON value for null.
Q 3 - Which of the following is supported by MongoDB?
B - Relationships between Collections (Primary Key Foreign Key)
Answer : C
Explanation
MongoDB does not support things like ACID Transactions or atomicity across collections or relationships like SQL.
Q 4 - Which option should be used to update all the documents with the specified condition in the MongoDB query?
A - updateAll instead of update
B - specify {multi : true} as the third parameter of update command
C - specify {all: true} as the third parameter of update command
D - specify {updateAll: true} as the third parameter of update command
Answer : B
Explanation
{multi:true} should be used for this purpose. By default, MongoDB will update only the first document.
Q 5 - Which are the ONLY ways to project portions of an array?
Answer : D
Explanation
$elemMatch, $slice, and $ are the only way to project portions of an array. For e.g. you cannot use {tags.0:1} for projection.
Q 6 - What is the equivalent command in MongoDB for the following SQL query?
SELECT * FROM posts WHERE author like "%john%"
A - db.posts.find( { author: /john/ } )
B - db.posts.find( { author: {$like: /john/} } )
Answer : A
Explanation
db.posts.find( { author: /john/ } )
Answer : B
Explanation
The minimum number of sensible number of voting nodes is 3.
Q 8 - Which of the following commands create an unique index on author field of the posts collection?
A - db.posts.createIndex({"author":1 }, {"unique": true});
B - db.posts.createIndex({"author": unique });
Answer : A
Explanation
MongoDB cannot create a unique index on the specified index field(s) if the collection already contains data that would violate the unique constraint for the index. The syntax for the same is db.collection.createIndex( { a: 1 }, { unique: true } )
Q 9 - Which of the following aggregation query will sort the posts collection with author key ascending:
A - db.posts.aggregate([ {$sort:{ author:1 } } ])
B - db.posts.aggregate([ {$sort:{ author:-1 } } ])
C - db.posts.aggregate([ {author: {$sort: 1} } ])
D - You need to first use $group or $project or $match command before $sort in the pipeline
Answer : A
Explanation
In the aggregation pipeline, it is not necessary to have a $group or $project or $match before the $sort operation.
Q 10 - Which command can be used to rebuild the indexes on a collection in MongoDB?
A - db.collection.createIndex({reIndex:1})
Answer : C
Explanation
If you need to rebuild indexes for a collection you can use the db.collection.reIndex() method to rebuild all indexes on a collection in a single operation. This operation drops all indexes, including the _id index, and then rebuilds all indexes.