You can get data out of tables using the SELECT command.

Get all rows and columns:

SELECT * FROM people;
 age |  name  
-----+--------
  37 | Flavio
   8 | Roger

Get only the name column:

SELECT name FROM people;
  name  
--------
 Flavio
 Roger

Count the items in the table:

SELECT COUNT(*) from people;
 count 
-------
     2

You can filter rows in a table adding the WHERE clause:

SELECT age FROM people WHERE name='Flavio';
 age 
-----
  37

The results of a query can be ordered by column value, ascending (the default) or descending, using ORDER BY:

SELECT * FROM people ORDER BY name;
SELECT * FROM people ORDER BY name DESC;

More database tutorials: