MongoDB C100DBA Exam - Topic 6 Question 117 Discussion

Actual exam question for MongoDB's C100DBA exam

Question #: 117
Topic #: 6

What does the following query do when performed on the posts collection? db.posts.update({_id:l},{Title:This is post with ID 1"})

ASyntax error

BReplaces the complete document with _id as 1 with the document specified in second parameter

CUpdates the Title of the post

DUpdating a document is possible only with $set

Show Suggested Answer

Suggested Answer: B

by Shawna at Nov 24, 2025, 11:24 AM

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Graciela

1 month ago

B is misleading. It doesn't replace the whole document.

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Nathalie

1 month ago

A is wrong too. No syntax error here.

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Bernadine

2 months ago

Not necessarily. C is valid without $set.

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Marci

2 months ago

But what about D? Isn't $set needed?

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Laura

2 months ago

I agree, C makes sense. Just the title changes.

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Lashawna

2 months ago

I think it's C. It updates the Title of the post.

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Alex

2 months ago

I thought you needed $set for updates, this is confusing!

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Jeffrey

2 months ago

Wait, can you really update without $set?

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Sheridan

3 months ago

Definitely not a full document replacement.

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Jettie

3 months ago

I think it just updates the Title, right?

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Lourdes

3 months ago

I'd rather update my resume than try to figure out this MongoDB query.

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Nobuko

4 months ago

This query is like a surgeon trying to perform heart surgery with a butter knife.

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Chery

4 months ago

D) Updating a document is possible only with $set

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Josphine

4 months ago

B) Replaces the complete document with _id as 1 with the document specified in second parameter

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James

4 months ago

C) Updates the Title of the post

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Argelia

4 months ago

I feel like I read that you can only update documents using $set, but I’m not sure if that applies here.

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Bette

4 months ago

I practiced a similar question, and I think it’s supposed to update the Title of the post, but I’m not completely confident.

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Jamal

5 months ago

I remember something about the update method, but I’m not sure if it replaces the whole document or just updates a field.

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I think the key here is that the query is using the update() method without the $set operator. Based on that, my guess is that option B is correct - it replaces the entire document with the _id of 1 with the new document specified in the second parameter.

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Idella

5 months ago

I'm a bit confused by this one. The question mentions the posts collection, but the query doesn't have a filter to select a specific document. And the second parameter doesn't look like the normal update syntax. I'm going to have to review my notes on MongoDB update operations before answering this.

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Meaghan

5 months ago

I think this query might have a syntax error because of the missing quotation marks around the title.

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Lorean

6 months ago

That's a syntax error for sure.

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Verlene

6 months ago

Okay, let me see. The query is using the update() method, so it's definitely an update operation. But the second parameter doesn't look like the typical $set format. I'm going to go with option C and say it updates the Title field.

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Gerald

6 months ago

Hmm, I'm not sure about this one. The question says it's updating the posts collection, but the query doesn't have the $set operator that I thought was required for updates. I'll have to think this through carefully.

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Simona

6 months ago

I think this query is updating the Title field of the document with the _id of 1. The second parameter looks like it's specifying the new Title value.

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