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So now that it's clear that we are free to define a schema for our documents and to structure them in

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exactly the way we want them to be structured for our use case or application, let's have a look at the

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different data types we can use in mongodb,

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so basically the types of data we can save in our fields, in our documents.

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There we for example have text, we already saw text data types in this course, text always uses quotation

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marks around the value and important here,

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I'm talking about the values so the part on the right side of the colon in your json documents. So

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you can save text like names,

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you also got no hard limitation here,

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the only limitation you have regarding the maximum amount of characters in your text are the 16mb

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overall size for the whole document,

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if your text is greater than that, well then your document becomes too big and your text is too long.

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We also have booleans, booleans are simple values,

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true or false, is something the case or not, is a user or an administrator or not,

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you could save that as a true or false value and that value is called a boolean. Another core data

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type

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are numbers of course

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and actually, we got a couple of different numbers in mongodb, we got integers for example and you see

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int32 here because mongodb knows different kinds of integers, int32 integers are integers

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that are 32bits long

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and therefore if you try to store values that are longer than that, they will overflow that range and

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you will end up with a different number, for longer numbers,

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mongodb has a solution though, a long number, an int64 integer which you can also assign to store values.

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In the shell by the way if you just enter a normal value,

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it is treated as a float value,

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that is because the normal shell as we use it in the course is based on javascript and javascript doesn't

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differentiate between integers and floating point values,

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so values with a decimal place,

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therefore everything will be stored as a 64bit float value in the shell,

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that is the default value and we'll play around with that a bit and see more of that in the numbers

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module of this course

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but be aware that mongodb is able to store smaller integers and bigger integers,

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the solution you choose here of course kind of defines how much space will be allocated and therefore

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how much space will be eaten up. And you also can store decimal numbers so numbers with decimal places,

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I already said that the default in the shell is to store a floating point value,

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you also got a special type, number decimal and that is provided by mongodb to store high precision

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floating point values because normal floating point values also called doubles are basically rounded,

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so they're not super precise after their decimal place.

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For a lot of use cases, it's enough though, like for prices in a shop, you got enough precision for that

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but if you're doing scientific calculations or anything like that, you might need a very high precision

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and there is a special type that offers this, a very high decimal place precision where you got 34

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decimal places,

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so after the comma which are not rounded but guaranteed to be correct and precise. It's simply a computing

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limitation that we got no 100% precision all the time

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but that rounding occurs. Now besides these basic values even though some number values here already

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are a bit more advanced, we also got the objectId value, the objectId object is a special object automatically

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generated by mongodb to give you a unique ID which is not just a unique random string but also a string

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that contains a temporal component, so that if you create two elements after each other, two documents after

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each other, you are guaranteed to have the right order due to that ID because the older element will

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have an ID that comes prior to the other one,

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so there is this sorting built into the objectId because it respects a timestamp.

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Speaking of timestamps, you can also save a date in your database, there is a special ISO date type which

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you can well use, you can construct the date and save that to your database

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and that is then a date which you can work with to do a date calculations and so on.

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And there also is a timestamp type, the timestamp is mostly used internally,

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you can create it automatically, mostly you let mongodb create that for you and that is guaranteed

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to be unique too,

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so even if you create two documents at the same time, they will not have exactly the same timestamp

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because it will basically take into account the current time

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and then also add an ordinal value, so that two documents at the same time still don't get the same time

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stamp but respect the order in which the insert command was issued for example.

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So you got that timestamp too and you could say that object, that the kind of is based on that timestamp

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and then just uses some algorithm to spit out a seemingly random string.

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Last but not least, you saw that you can embed other documents,

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that's of course important too, you can embed documents and these documents can then in turn embed other documents

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or hold any fields with any of the values you see here

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and you can also have arrays as values and the arrays are simply lists of values,

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you can have a list of strings, a list of booleans, a list of numbers or a list of other embedded documents

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or even a list of lists, a list of arrays, that is possible too.

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So these are the data types and throughout the course, you will see them again,

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so we'll work with them

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and for example there will be a whole module where I will work with numbers to give you a feeling for

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why we have these different types of numbers. In the next lectures,

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I just want to play around with these types a bit and give you a feeling for how we create the more

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advanced types like dates here and how we can save them and work with them.