SELECT

The SELECT statement in SQL is majorly used for fetching data from the database. It is one of the most essential elements of SQL.

Syntax

Here's how your SELECT command will look like:

SELECT column1, column2, ...
FROM table_name;

If you want to select all the columns of a table, you can use * like this:

SELECT * FROM table_name;

Example

For instance, consider we have a table EMPLOYEES with columns name, designation, and salary. We can use SELECT in the following way:

SELECT name, designation FROM EMPLOYEES;

This will retrieve all the names and designations of all employees from the table EMPLOYEES.

SELECT DISTINCT

The SELECT DISTINCT statement is used to return only distinct (different) values. The DISTINCT keyword eliminates duplicate records from the results.

Here's how you can use it:

SELECT DISTINCT column1, column2, ...
FROM table_name;

For example, if we want to select all unique designations from the EMPLOYEES table, the query will look like this:

SELECT DISTINCT designation FROM EMPLOYEES;

SELECT WHERE

SELECT statement combined with WHERE gives us the ability to filter records based on a condition.

Syntax:

SELECT column1, column2, ...
FROM table_name
WHERE condition;

For example, to select employees with salary more than 50000, you can use this query:

SELECT * FROM EMPLOYEES WHERE salary > 50000;

SELECT ORDER BY

Using SELECT statement in conjunction with ORDER BY, we can sort the result-set in ascending or descending order.

Syntax:

SELECT column1, column2, ...
FROM table_name
ORDER BY column ASC|DESC;

For example, to select all employees and order them by their name in ascending fashion:

SELECT * FROM EMPLOYEES ORDER BY name ASC;

Remember that the default sort order is ascending if the ASC|DESC parameter is not defined.