Test your skills: Querying Embedded Documents in Arrays

You are building a query to retrieve documents from a collection that stores information about your company’s inventory. The query is based on the inventory array, which includes multiple embedded documents.

Each embedded document contains the product and in_stock fields. You want to find the warehouses that have at least 20 items of a specific product.

Which operator should the query include to return the correct documents?

You are building a query to search the customers collection. The query is based on the travel array, which is made up of embedded documents that describe visited countries.

Each embedded document includes the country field and the visits field. You want to find customers who have visited Canada exactly three times.

Which find statement should you use?

You are building a query to search the customers collection. The query is based on the travel array, which is made up of embedded documents that describe visited countries.

Each embedded document includes the country, visits, and rating fields, in that order. You want to return all documents for customers who have visited Thailand two times and who have assigned the country a rating of 9. You run the following query, but it returns no documents:

db.customers.find({ travel:
{ visits: 2, rating: 9, country: "Thailand" } } );

You know that the collection contains documents that meet your search criteria. Why does the statement fail to return any documents?

You are building a query to search the customers collection. The query is based on the travel array, which is made up of embedded documents that describe visited countries.

Each embedded document includes the country, visits, and rating fields. You want to find customers who have visited a country two or more times and who have rated the country as 7 or less.

Which find statement should you use?

You are using Visual Query Builder to create a query to search the customers collection. The query is based on the travel array, which is made up of embedded documents that describe visited countries. Each embedded document includes the country, visits, and rating fields.

You want to find customers who have traveled to Costa Rica. In the query form, you select the Has array element(s) matching option and add the name of the array to the Array box. Next, you click the Add button to add a section for defining the search condition.

What should you type in the first drop-down list in the new search condition section?