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  3. Introduction to MongoDB in Python

Exercise

Our 'born' approximation, and a special laureate

We saw earlier that the laureates collection encodes uncertainty about birthdate in a special way. When a birthdate is unknown, the "born" field has the value "0000-00-00". Thus,

db.laureates.count_documents({"born": "0000-00-00"})

counts the number of such laureates. Or does it?

We also saw that the total number of laureate prizes is more than the number of laureates -- some were awarded more than one prize. There is one in particular with a whopping three prizes, and this laureate holds key information to aid our quest to determine the proportion of prizes awarded to immigrants.

Instructions 1/2

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  • 1
    • Use a filter document (criteria) to count the documents that don't have a "born" field.
  • 2
    • Use a filter document (criteria) to find a document for a laureate with at least three elements in its "prizes" array. In other words, does a third element exist for the array? Remember about the zero-based indexing!