Question $7$

Consider that our posts collection contains an array field called tags that contains tags that the user enters.

$\{\_$id: $1,$ tags: $["$tutorial$",$ "fun", "learning"$],$ post$\_$text: "This is my first post", topic$\_$category: "lecture"$\}$

What does the following command return?

db$.$posts.find$(\{$ "tags$\mathrm{.}0"$: "tutorial" $\})$

All the posts whose tags array contains tutorial

All the posts which contains only one tag element in the tag array

All the posts having the first element of the tags array as tutorial

All the posts which contains $0$ or more tags named tutorial

$5$ points $$

Question $8$

Consider that the posts collection contains an array called ratings which contains ratings given to the post by various users in the following format:

$\{\_$id: $1,$ post$\_$text: "This is my first post", ratings: $[5,4,2,5],//$other elements of document $\}$

Which query will return all the documents where the array ratings contains at least one element between $3$ and $6?$

db$.$inventory.find$(\{$ ratings: $\{$ $elemMatch: $\{$ $gt: $3,$ $lt: $6\}\}\})$

db$.$inventory.find$(\{$ ratings: $\{$ ratings: $\{$ $gt: $5,$ $lt: $9\}\}\})$

db$.$inventory.find$(\{$ ratings: $\{$ ratings.$: $\{$ $gt: $5,$ $lt: $9\}\}\})$

db$.$inventory.find$(\{$ ratings: $\{$ $elemMatch: $\{$ $gte: $3,$ $lte: $6\}\}\})$

$5$ points $$

Question $9$

Consider that the posts collection contains an array called ratings which contains ratings given to the post by various users in the following format:

$\{$ id: $1,$ post$\_$text: "This is my first post", ratings: $[5,4,2,5],//$other elements of document $\}$

Which query will return all the documents where the ratings array contains elements that in some combination satisfy the query conditions?

db$.$inventory.find$(\{$ ratings: $\{$ $elemMatch: $\{$ $gt: $3,$ $lt: $6\}\}\})$

db$.$inventory.find$(\{$ ratings: $\{$ ratings: $\{$ $gt: $5,$ $lt: $9\}\}\})$

db$.$inventory.find$(\{$ ratings: $\{$ ratings.$: $\{$ $gt: $5,$ $lt: $9\}\}\})$

db$.$inventory.find$(\{$ ratings: $\{$ $elemMatch: $\{$ $gte: $3,$ $lte: $6\}\}\})$

$5$ points $$

Question $10$

Consider the following posts document:

$\{$ id: $1,$ post$\_$text: "This is my first post", author: "Tom", tags: $["$tutorial$",$"quiz","facebook","learning","fun"$]\}$

Which of the following queries will return the documents but with only the first two tags in the tags array?

db$.$posts.find$(\{$author:"Tom"$\},\{$tags:$\{$$slice:$2\}\})$

db$.$posts.find$(\{$author:"Tom"$\}).$limit$(\{$tags:$2\})$

db$.$posts.find$(\{$author:"Tom"$\}).$limit$($$slice:$\{$tags:$2\})$

Both a and c are valid. $slice works both with projection and limit$.$