You describe the data for your application using the "nouns" that you've identified. And you represent the nouns in your database using multiple tables. The associations between tables are known as "data relationships".
[MUSIC] 0:00 Hi, everyone, I'm Guil, a developer and instructor here at Treehouse. 0:09 In this course, you'll learn how to define data relationships using SQL and 0:13 Sequelize. 0:17 A Node.js ORM or Object-Relational Mapping library for SQL databases. 0:18 You've learned that a SQL database is called a relational database. 0:23 The database structure which you organize into tables. 0:27 Allows you to store, access, and connect data, 0:30 in relation to other data in the database. 0:33 That way you can think about and use data in terms of 0:36 related sets as opposed to individual values or rows. 0:39 For example, when designing an applications database, 0:43 it's a common practice to start by listing all of the things that the application 0:46 will be working with. 0:50 Or all of the nouns. 0:51 Imagine that you've been tasked with creating an application like IMDb, 0:53 that will allow users to view a list of movies. 0:57 Each movie will display its title, release year, director's name, 1:00 and optionally the primary actors' names. 1:04 You identify your first noun as movie, which will have title and 1:07 release year attributes or properties. 1:11 But what about the movie's director and actors? 1:13 Do you add additional movie properties? 1:16 Or do you treat directors and actors as separate nouns? 1:19 Director and actor for example. 1:22 They'll both have firstName and lastName properties. 1:24 So you decide to think of a director, or actor, as a single noun: person. 1:26 You can describe the data for your application 1:31 using the nouns that you've identified for your application, movie and person. 1:34 And you represent the nouns in your database using multiple tables. 1:38 There are also relationships between your nouns or tables. 1:42 For example, a movie will be associated with a person as its director, 1:46 and a movie will be associated with one or more people as its actors. 1:50 These associations between movie in person, are known as data relationships. 1:54 As you follow along in this course, you're going to define data relationships for 2:00 a simple node application that creates and retrieves movie data. 2:04 You'll define data relationships and Sequelize models, and 2:08 create related data, 2:11 like movie and person records. using those models. 2:12 Then you'll retrieve related data with Sequelize queries. 2:16 To get the most from this course, you should be familiar with SQL and Sequelize. 2:19 If you need a refresher, review the Treehouse courses and 2:24 workshops posted in the teachers notes. 2:27 Next, you'll start exploring data relationships in a Sequelize database, 2:30 why they are useful, and the different types of relationships. 2:34 Then you'll download and run the Node.js project, 2:38 and begin creating data relationships using Sequelize. 2:40
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