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In this video.

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Let's talk about types of database relationship, which means that how we can relate to or more documents

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together.

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But before we get into that, let's go over what we call the planning stage.

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So as we discussed in the previous video, let's go over again because it's really important.

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Now, let's say that you got the idea about the entire application.

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So after you go the idea, the first step is what you name your database as we said.

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So in this case, let's say you are building a blog application.

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So here the name of a database is called What Blog Application?

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And for the blog application you may need a different collection.

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For example, you're going to have post collection and call this one as collection one.

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You need collection to core users and you need another collection called Comments.

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Now you can see that these collections are independent.

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They don't know each other.

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And let's say that if you want to know which post was made by a certain user and what comments was made

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by a user and what post has a specific comment.

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And this is what we call database relationship.

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So with that being said, let's have a look at types of database relationship.

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The first type of database relationship is what you call 1 to 1 relationship.

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What does it mean?

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Let's take it that we are building a blog application and we have three collections posts, users and

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comment.

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When we say 1 to 1, it simply means that one user can have one post or can create a post and a post

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belongs to a user, meaning one is to one, and for this kind of relationship is not mostly used.

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The next type of relationship is what you call one to many relationship.

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Again, let's take a block application into this context.

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It simply means that one user can have or create many posts, but a post belongs to a single user.

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That is it.

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And this kind of relationship is mostly used 100% in any application.

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I can tell you that there is at least one to many relationship, and the next type of relationship is

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what we call many to many relationships.

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Well, what does it mean?

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It simply means that one user can have many posts, but a post belongs to many users.

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Again, this kind of relationship is not mostly used and we use this kind of relationship mostly in

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e commerce application.

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We can have a product having many orders and the same orders can have many users.

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So let's say that we have a product called iPhone, that iPhone many users can order that particular

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product, meaning that that particular product can have many orders and that orders belongs to that

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particular product.

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And again, this kind of relationship is not that mostly used, but the one which is really important

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is what we call one to many relationship.

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And this is what I'm going to show you if I show you this one.

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Implementing these ones are easy.

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But like I said, you are going to work with what is called one to many relationships.

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All right.

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The next video, I will show you how we can relate document together.

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So we are in the process of what modeling data now we know ties of relationship.

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Now let's go ahead and talk about how we can relate to or more document together in the next video.