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

What is **SQL**?

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

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

<div style='height:300px;overflow:scroll;'><table style='border-collapse: collapse'><tr><th>id</th><th>name</th><th>continent</th><th>region</th><th>surfacearea</th><th>capital</th><th>population</th></tr><tr><td>1</td><td>Japan</td><td>Asia</td><td>Eastern Asia</td><td>377829</td><td>Tokyo</td><td>126714000</td>
</tr><tr><td>2</td><td>Latvia</td><td>Europe</td><td>NULL</td><td>64589</td><td>Riga</td><td>2424200</td>
</tr><tr><td>3</td><td>Mexico</td><td>North America</td><td>Central America</td><td>1958201</td><td>Mexico City</td><td>98881000</td>
</tr><tr><td>4</td><td>Netherlands</td><td>Europe</td><td>Western Europe</td><td>41526</td><td>Amsterdam</td><td>15864000</td>
</tr><tr><td>5</td><td>Portugal</td><td>Europe</td><td>Southern Europe</td><td>91982</td><td>Lisbon</td><td>9997600</td>
</tr><tr><td>6</td><td>Sweden</td><td>Europe</td><td>Nordic Countries</td><td>449964</td><td>Stockholm</td><td>NUll</td>
</tr><tr><td>7</td><td>Ukraine</td><td>Europe</td><td>Eastern Europe</td><td>603700</td><td>Kyiv</td><td>50456000</td>
</tr><tr><td>8</td><td>United States</td><td>North America</td><td>NULL</td><td>9363520</td><td>Washington</td><td>278357000</td>
</tr><tr><td>9</td><td>Thailand</td><td>Asia</td><td>NULL</td><td>513115</td><td>Bangkok</td><td>61399000</td>
</tr><tr><td>10</td><td>Paraguay</td><td>South America</td><td>North America</td><td>406752</td><td>Asunción</td><td>5496000</td>
</tr><tr><td>11</td><td>Philippines</td><td>Asia</td><td>Southeas Asia</td><td>300000</td><td>Manila</td><td>75967000</td>
</tr><tr><td>12</td><td>New Zealand</td><td>Oceania</td><td>Australia and New Zealand</td><td>270534</td><td>Wellington</td><td>18886000</td>
</tr><tr><td>13</td><td>Norway</td><td>Europe</td><td>Nordic Countries</td><td>323877</td><td>Oslo</td><td>4478500</td>
</tr><tr><td>14</td><td>Monaco</td><td>Europe</td><td>Western Europe</td><td>1.50</td><td>Monaco</td><td>NUll</td>
<tr><td>15</td><td>Malta</td><td>Europe</td><td>Southern Europe</td><td>316</td><td>Valletta</td><td>380200</td>

</tr></table></div>

SELECT is an operator language that returns a data set (sample) from the database. In order to use the SELECT operator, we should specify what exactly we want to select and where we want to select it from.

We used the SELECT statement in the previous query to get a *single continent column* from the *country table*.
We need to specify the column name immediately after the SELECT keyword, and the FROM keyword specifies the name of the table from which we want to retrieve data.

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.