Selecting

CommentsProcedural SQL (PSQL) Statements

Selecting `FROM` a table or view

When selecting from a single table or view, the FROM clause requires nothing more than the name.An alias may be useful or even necessary if there are subqueries that refer to the main select statement (as they often do — subqueries like this are called correlated subqueries).

Examples

select id, name, sex, age from actors
where state = 'Ohio'

select * from birds
where type = 'flightless'
order by family, genus, species

select firstname,
  middlename,
  lastname,
  date_of_birth,
  (select name from schools s where p.school = s.id) schoolname
from pupils p
where year_started = '2012'
order by schoolname, date_of_birth

Important

Never mix column names with column aliases!

If you specify an alias for a table or a view, you must always use this alias in place of the table name whenever you query the columns of the relation (and wherever else you make a reference to columns, such as ORDER BY, GROUP BY and WHERE clauses).

Correct use:

SELECT PEARS
FROM FRUIT;

SELECT FRUIT.PEARS
FROM FRUIT;

SELECT PEARS
FROM FRUIT F;

SELECT F.PEARS
FROM FRUIT F;

Incorrect use:

SELECT FRUIT.PEARS
FROM FRUIT F;

Selecting

Selecting FROM a table or view

Examples

Selecting `FROM` a table or view