INTRODUCTION

ROWS AND COLUMNS

Many apps you interact with store data like a username, password, or friends list.

This kind of data lives in a Database. Most databases are collections of tables storing different pieces of data.

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What kind of data do you think a website like Hashnode stores?

1. data like users' music videos.

2. data like users' names, email, active streak, process.

data like users' names, email, active streak, process.

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• SQL is a language for modifying, inserting, and accessing data from tables in a database.

Q) What is SQL?

1. A programming language we use to select, modify, and insert data in databases.

2. A programming language we use to code website interfaces

A programming language we use to select, modify, and insert data in databases.

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• Tables are like spreadsheets storing information about a specific kind of data, like this table storing users' IDs, names, and emails.

Each row of a table represents a new item, like how the first row contains data about a user item's ID, name, and email address.

Q) If every row stores an item, how many user items does this table store?

1. Three user items, because it has three rows.

2. We can't know how many user items it stores.

Three user items, because it has three rows.

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Properties of each user item, like a name or email

Q) If rows stand for items, what do you think columns are?

1. Each column stands for a different user item

2. Properties of each user item, like a name or email

Properties of each user item, like a name or email

Columns store properties of items, like how the email column stores the email of each user item.

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Select Data

If SQL is a language for manipulating data, which language instruction might we use to select data?

1 )DELETE

2 )SELECT

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Use the SELECT statement, followed by name to select the values on the name column.

Users

Practice

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What do you think the FROM users statement does?

SELECT name 
FROM users;

1) It says which table we want to select the name column from

2) It renames a column

It says which table we want to select the name column from

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Each table has a name. Code FROM followed by the table name users to select data from the users table.

PRACTICE

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When requesting data with SQL statements like SELECT, we say that we're making a query.

Users
userID	name	email
1	Sam	sam17@mail.com
2	Remy	rem@mail.com
3	Luis	luis_99@mail.com

PRACTICE

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Code a query that selects all titles from the movies table with SELECT title followed by FROM movies;.

PRACTICE

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To tell apart SQL keywords from column and table names, we write them in upper case. Tap on the code and type FROM.

PRACTICE

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While not necessary, it's considered good practice to finish your SQL queries with a semicolon ;.

PRACTICE

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