Retrieving Individual Columns

What is SQL?

SQL is a programming language for user interaction with databases, used to query, update, and manage databases.

Database

A database is an organized structure designed to store, modify, and process large amounts of data.

Let’s get started! In this course, we will work with a country database containing a country table. Let's look at this table.

id	name	continent	region	surfacearea	capital	population
1	Japan	Asia	Eastern Asia	377829	Tokyo	126714000
2	Latvia	Europe	NULL	64589	Riga	2424200
3	Mexico	North America	Central America	1958201	Mexico City	98881000
4	Netherlands	Europe	Western Europe	41526	Amsterdam	15864000
...	...	...	...	...	...	...
15	Malta	Europe	Southern Europe	316	Valletta	380200

SELECT is an operator in the SQL language that retrieves a data set (sample) from the database. To use the SELECT operator effectively, we need to specify exactly what we want to select and where we want to select it from.

In our previous query, we utilized the SELECT to retrieve a single continent column from the country table. It's important to note that you must specify the column name immediately after the SELECT keyword, and the FROM keyword specifies the name of the table from which we wish to retrieve data.

Task

Now, let's retrieve a capital column from the country table.

_{Once you've completed this task, click the button below the code to check your solution.}

Everything was clear?

Section 1. Chapter 1

Course Content

Introduction to SQL

1. Retrieving Data

Retrieving Individual Columns Retrieving Multiple Columns Retrieving All Columns Retrieving Distinct Rows Limiting Results Challenge: Find the Population of the Countries Challenge: Find All Countries Challenge: Find All Countries With Their IDs Challenge: Find Country Capitals Challenge: Find the Regions in Which All Countries Are Located

2. Sorting Retrieved Data

Sorting Data Challenge: Population Sort Sorting by Multiple Columns Challenge: Dual-Sort Query Specifying Sort Direction Challenge: Sort the Countries by Region and Capital Challenge: Sort Capitals in Descending Order Challenge: Sort Countries in Ascending Order Challenge: Find Countries, Their IDs, and Their Populations Challenge: Find Countries, IDs, Populations, Regions, and Sort Them Challenge: Find All Continents and Sort Them in Ascending Order

3. Filtering Data

Using the WHERE Clause Challenge: North America Population Sort The WHERE Clause Operators Challenge: Population Threshold Query Checking for a Range of Values Checking for NO Value

4. Advanced Data Filtering

Using the AND Operator Challenge: Europe Region Sort Using the OR operator Challenge: America Regions Filter Using the NOT Operator Challenge: Non-Europe Capitals Sort

5. Aggregate Functions

The AVG() Function Challenge: Large Surface Area Average The COUNT() Function Challenge: Continental Count The MAX() Function The MIN() Function Challenge: Surface Area Selection The SUM() Function