Kursinnehåll

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

Retrieving Individual Columns

What is SQL?

Database

Why SQL Matters

SQL is essential for managing and querying databases efficiently. It is widely used due to its standardization, scalability, and ability to ensure data integrity. SQL's integration with other technologies makes it a versatile tool in various applications, supporting real-time data processing and decision-making.

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

SQL Syntax Explanation

To retrieve data from a database, SQL uses the SELECT statement. Here's the basic syntax:

SELECT: Specifies the columns to retrieve;
FROM: Specifies the table from which to retrieve the data.

For example, to get the sample column from the sample_table table, the syntax is:

sql

The following query will return all entries in the continent column from the country table:


              1
            
SELECT continent FROM country;

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.

Uppgift

Swipe to start coding

Write an SQL query to retrieve a capital column from the country table.

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

Lösning

Byt till skrivbordet för praktisk övningFortsätt där du är med ett av alternativen nedan

Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 1. Kapitel 1

Retrieving Individual Columns

What is SQL?

Database

Why SQL Matters

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

SQL Syntax Explanation

To retrieve data from a database, SQL uses the SELECT statement. Here's the basic syntax:

SELECT: Specifies the columns to retrieve;
FROM: Specifies the table from which to retrieve the data.

For example, to get the sample column from the sample_table table, the syntax is:

sql

The following query will return all entries in the continent column from the country table:


              1
            
SELECT continent FROM country;

Uppgift

Swipe to start coding

Write an SQL query to retrieve a capital column from the country table.

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

Lösning

Byt till skrivbordet för praktisk övningFortsätt där du är med ett av alternativen nedan

Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 1. Kapitel 1

Byt till skrivbordet för praktisk övningFortsätt där du är med ett av alternativen nedan