MongoDB for Developers with Python Transcripts
Chapter: MongoDB's shell and native query syntax
Lecture: Concept: Advanced queries
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So here's the list of the quering operators, all the complex ones.
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So we saw that normally we pass these prototypical json objects,
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ratings.values is five, and that just doesn't exactly match,
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but we saw that that doesn't really solve all our problems,
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often we want ranges or properties like
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I want all of the ratings that are greater than eight, things like that;
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so instead of putting a number into that prototypical json element,
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we're going to put an operator, so we might say $eq for equality
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that's kind of the same thing, but the others are not,
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so $gt for greater than, greater than or equal to,
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lt for less than, less than or equal to,
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not equal to, so you could say I want to see all the ones where
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there's no vote, or no rating of value ten, right,
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there's no rating that has a value of ten.
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And we talked about the in operator, this is kind of your two step join process
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that we'll talk much more about when we get to the Python side of things,
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there's also the inverse of that negation, not in the set.
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So here's an example how we might use the greater than or equal to operator
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to find all the books that have a rating of nine or ten
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that are super highly rated by at least one person,
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remember this is not like every single one in there has to be this,
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but there exists of rating which is a nine or a ten.
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We also have some joining operators or some combining operators joining,
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so we can go in and say and pretty easily by just having
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all the properties we're looking for in a single document,
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but if for some reason these are coming from multiple places
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you can actually combine them with the and operator
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so that's nice, but what you really sometimes need is the or clause,
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I want this or that, and there's no way to do that those prototypical json objects
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but the or operator will let you do this.
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You also have not and nor, so neither of these in an or,
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sort of the negation of an or;
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now I recommend you check out this link at the bottom for each one of them,
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like so where the operator appears, does it appear to the right hand side
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of the property or field name or the left hand side,
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it kind of depends on the type of operator you're using,
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so you can just click on this or the and and so on
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and in the docks and it'll give you a little example.
