`SUM()` - This function returns the sum of the values in a specific column. Let's take a look at the example:

SELECT SUM(population) 
FROM country 
WHERE continent='Asia';

**Explanation:** The `SUM()` function returns the sum of the population of all countries in Asia from the `country` table.

In this section, we will learn how to use the SQL SELECT statement to get a single table column, multiple table columns, and all table columns. We will also find out how to return unique values.

In this section, we will learn how to sort retrieved data using the ORDER BY clause. This clause, which must be the last in the SELECT statement, can be used to sort data on one or more columns as needed.\n

In this section, we will learn how to filter returned data using the SELECT statement’s WHERE clause. We will learn how to test for equality, inequality, more and less significant than value ranges, and NULL values.

In this section, we will learn how to combine WHERE clauses with the AND and OR operators. We will also find out how the NOT operator works.\n\n\n

In this section, we will learn what the SQL aggregate functions are and how to use them to summarize table data.

You have a database that contains one table called Students. There are 3 columns in this table: student_id, student_mark, student_name. How can you calculate the average mark?

Choose SQL statement to retrieve the average value of a student_mark column, where values of a student_name will be 'Mark'.

Choose  SQL statement to retrieve the number of students where mark is less than 4.

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
...	...	...	...	...	...	...
15	Malta	Europe	Southern Europe	316	Valletta	380200

Introduction to SQL

The SUM() Function

Task