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For this I started my mongod server again and I connected to it again and I got nothing in there.

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Now if you have something in there and you want to get rid of that, 

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you can always use a database and then simply run db drop database to get rid of the database and all

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the data that is in there

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and as you see, you can even run that on databases that don't exist and it will not complain.

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So then you should be in that same state and have absolutely no data in there except for the default

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databases which you need.

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Now with that, let's insert some persons again,

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so let's say we have a persons collection or let's first of all switch to a database,

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we could name it contact data and then there, let's use the persons collection and

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let's insert one person.

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Now you learned this before

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but in the end here, you enter one document, a document always is marked by the curly braces that's around

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it and then a document is made up of the key value pairs,

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so you have these fields like name is the field, the value for this field is Max and then the next field is

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separated with a comma like

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age 30,

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in this case this is a number

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hence we have no quotation marks around it

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and then we might also have some hobbies which could be an array,

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sports and cooking. And if I insert this, we get this auto-generated ID here which is guaranteed to be

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unique and which also has this temporal component,

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so if you have multiple documents, they are by default ordered after this ID because the ID reflects

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when they were created.

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So if I add another document here, let's say Manuel and I set the age to 31

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and I set the values here to cooking and let's say cars, then I inserted this document too, 

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ok.

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So this is insert one,

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now let's insert many and for this I'll reach out to the same collection and there, I'll use insert many

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like this

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and now the important thing here is you don't enter multiple documents separated by a comma because

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you don't pass them as arguments to this method.

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Insert many does indeed have a way where it accepts some data after this comma, so a second argument and

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I will dive into that second argument in a second

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but if you want to insert multiple documents, you just have to pass an array of these documents,

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so a list of these documents, a comma separated list.

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So then we could insert Anna, age 29 and there maybe add some hobbies

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and as you learned in the schema module, you don't have to have the same structure on all documents in

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the same collection,

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this is totally optional

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so it would be totally fine if you inserted Anna without hobbies but I'll insert Anna with the hobbies

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of sports and yoga and as you see, that worked too even though it was only one person but of course the

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main idea behind insert many is that you do enter multiple persons or multiple documents but you don't

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have to as you just saw, it's perfectly fine if you use insert many with one document only,

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you still need to put it into an array,

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it does not work otherwise.

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So if I now enter more persons here real quick and I'll leave out the hobbies to speed it up for those,

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so here we also have Maria and we have Chris,

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then here you see I inserted two documents separated by a comma also enclosed in square brackets,

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hence it's an array and this also worked.

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And with that, I got all these persons in the database and these are the insert methods you learned about.

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Now as I mentioned, there also would be the insert method, the insert method can still be used,

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it's just not recommended.

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Insert works with both a single document,

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so if we insert Phil here, this does work and you see the output is a bit different, we get a different

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result,

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now this does not mean that Phil didn't get an ID.

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If we quickly have a look into persons with find and pretty, we see that Phil does have an ID, so this

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output here just does not tell us the ID which also is an advantage of insert one and many,

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they give us a different output which is a bit more meaningful or helpful because it immediately gives

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us the ID in case we want to work with it,

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we don't have to query the database just to get that ID, which by the way is a real advantage because

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if you're building an application where you insert some data into the database, then often you want to

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get that ID back of that insert operation and immediately use it in your app.

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Let's say you build a user interface where users also can delete documents or objects they created, then

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you need that ID in your UI, in your frontend application so that if the user clicks the delete button,

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you already know which ID,

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so which document with which ID to delete.

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If you have an insert operation, that does not tell you the ID,

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it basically means that you need to wait for the insert to complete just to then query all documents and

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find that ID manually, so that your frontend continues to work.

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So this is a real thing,

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this inserted ID,

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it's not just a nice benefit, it's extremely helpful.

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So this is also another reason why insert is not that great

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but the other thing of course is we can use it for both a single person as you just saw or for multiple

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persons by adding an array here.

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So if I have Sandeep here with an age of 28 and I also have Hans here with an age of 38, then this

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also works, now you see it automatically did a bulk write,

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it gives us a different output here too,

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it still doesn't tell us the ID but on the other hand, we get useless results like that it did not remove

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any elements,

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well I did not expect it to do that on insert and therefore, insert one and insert many are definitely

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more helpful both from output perspective but also from an input, from a readability and error protection

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perspective.