SELECT

Retrieves the specified columns.

SELECT column1, column2 FROM table_name;

Retrieves all columns.

SELECT * FROM table_name;

Retrieves a column with an alias.

SELECT column_name AS alias FROM table_name;

Retrieves unique values, excluding duplicate rows.

SELECT DISTINCT column_name FROM table_name;

The following 'employees' table is used in the examples below.

Retrieves the name and department from the employees table.

sample_select.sql

SELECT name, department FROM employees;

+--------+------------+
| name   | department |
+--------+------------+
| user_a | org_a      |
| user_c | org_b      |
| user_e | org_a      |
+--------+------------+
3 rows in set

Retrieves all columns from the employees table.

sample_select.sql

SELECT * FROM employees;

+----+--------+------------+--------+
| id | name   | department | salary |
+----+--------+------------+--------+
|  1 | user_a | org_a      | 300000 |
|  2 | user_c | org_b      | 280000 |
|  3 | user_e | org_a      | 320000 |
+----+--------+------------+--------+
3 rows in set

Retrieves columns with aliases.

sample_select.sql

SELECT name AS full_name, salary AS monthly_salary FROM employees;

+-----------+----------------+
| full_name | monthly_salary |
+-----------+----------------+
| user_a    |         300000 |
| user_c    |         280000 |
| user_e    |         320000 |
+-----------+----------------+
3 rows in set

Retrieves a list of departments with duplicates removed.

sample_select.sql

SELECT DISTINCT department FROM employees;

+------------+
| department |
+------------+
| org_a      |
| org_b      |
+------------+
2 rows in set

You can also assign an alias to a calculated expression.

sample_select.sql

SELECT name, salary * 12 AS annual_salary FROM employees;

+--------+---------------+
| name   | annual_salary |
+--------+---------------+
| user_a |       3600000 |
| user_c |       3360000 |
| user_e |       3840000 |
+--------+---------------+
3 rows in set

The basic syntax for SELECT, AS, and DISTINCT is supported across all major databases.

SELECT name AS full_name, salary AS monthly_salary FROM employees;
SELECT DISTINCT department FROM employees;

In PostgreSQL, DISTINCT ON (column) returns only the first row for each distinct value of the specified column.

Retrieves the highest-paid employee from each department.

SELECT DISTINCT ON (department) name, department, salary
FROM employees
ORDER BY department, salary DESC;

SELECT is the most frequently used statement in SQL and reads data from a table. Specifying only the columns you need reduces the amount of data transferred over the network and improves performance.

Aliases defined with AS can include non-ASCII characters, but be careful when referencing column names from application code — names that contain spaces must be wrapped in backticks (MySQL) or double quotes (standard SQL).

MySQL (backticks)

SELECT name AS `full name` FROM employees;

Standard SQL / PostgreSQL (double quotes)

SELECT name AS "full name" FROM employees;

Use SELECT together with WHERE for filtering, ORDER BY for sorting, and LIMIT for limiting the number of rows returned.