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Now what else can we do with update besides setting some values?

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Let's look into our users again and let's say Manuel got older, he's 30 but let's say we want to increase

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that to 31.

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Now obviously, this is pretty straightforward to us,

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we could use $set and set age to 31

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but in a typical application, you will not know the age of all your users,

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so it would be nice if you wouldn't have to find all users or the user you want to update first to get

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the current age then recalculate the new age and then issue your update request, would be nice

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if for simple and common transformations like this, mongodb would do that

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and indeed it can. Incrementing a number,

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so increasing it is such a common task that mongodb has a built-in operator for this.

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So let's quickly grab the ID or let's filter by name to mix it up,

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so let's filter for Manuel, db users update one

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and then here, I'm looking for a name equal to Manuel,

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this will find the first entry or the first document with a name of Manuel in the collection

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and then here in a second argument, I don't use $set but I use the inc,

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so $inc, by the way you can also combine this. You can have $inc

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and then here you have some information which I'll add in a second

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and then as a second element in this second argument, so in this object with the purple curly brace, you

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can of course add $set and describe some other changes,

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so you can do multiple different things in the same update.

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But here I'll just use $inc and I will say that the age should be incremented by 1,

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this is what this will do

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and we could also increment by two,

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so if I do that for example and I find all results, Manuel now has an age of 32,

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it was 30 before.

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Now you can also decrement with this method even though it's called inc,

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you can also say -1 for example

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and now it will be 31 as you can see here.

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So with inc, you can go in both directions

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and as I mentioned, you can combine it and just to show this because it's really important,

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you can absolutely say increment by 1 and then $set

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and for example set isSporty which is missing to false because Manuel doesn't have sports as a hobby.

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If you do that, then you see it also succeeded and it simply did both

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and if we check Manuel again, he's now 32 and isSporty was added with a value of false.

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Now of course you could also get fancy and you could try setting the same value you're incrementing,

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so I'm incrementing age by 1 and then I'm setting age to 30,

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now let's see what happens now.

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If I do that, then I get an error,

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I get an error that updating the path age would create a conflict at age because I simply got two operations

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working on the same field

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and this is not allowed here,

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so it will simply fail.

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So you can use inc and set

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and the other operators I'll show you together but working on the same field will not be possible.