Which of the following is not something queries can do?

• Retrieve data from a database

• Update data in a database

• Delete data from a database

• Send emails or notifications to users

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Explanation: Queries are a way to ask a database to give you information. Think of it like asking a librarian to find you a specific book in a library. You can tell the librarian what you're looking for, and they'll search through the shelves to find it for you.

Similarly, you can use queries to ask a database for specific information. For example, you might ask a database to give you a list of all the customers who bought a certain product in the past month. The database will search through its records and return the relevant data to you.
Queries can also be used to update, delete, or add new data to a database. So you could use a query to change a customer's address or add a new product to the database.
However, queries are not designed to send emails or notifications to users. For that, you would need to use a separate tool or service. Think of it like a librarian not being able to send you an email when the book you want becomes available. They can only help you find the book itself.