postgresql
SELECT

SELECTEER met WAAR

In dit onderwerp baseren we ons op deze tabel met gebruikers:

CREATE TABLE sch_test.user_table
(
  id serial NOT NULL,
  username character varying,
  pass character varying,
  first_name character varying(30),
  last_name character varying(30),
  CONSTRAINT user_table_pkey PRIMARY KEY (id)
)

+----+------------+-----------+----------+------+
| id | first_name | last_name | username | pass |   
+----+------------+-----------+----------+------+
| 1  | hello      | world     | hello    | word |   
+----+------------+-----------+----------+------+
| 2  | root       | me        | root     | toor |   
+----+------------+-----------+----------+------+

Syntaxis

Selecteer alles:

SELECT * FROM schema_name.table_name WHERE <condition>;

Selecteer enkele velden:

SELECT field1, field2 FROM schema_name.table_name WHERE <condition>;

Voorbeelden

-- SELECT every thing where id = 1
SELECT * FROM schema_name.table_name WHERE id = 1;

-- SELECT id where username = ? and pass = ?
SELECT id FROM schema_name.table_name WHERE username = 'root' AND pass = 'toor';

-- SELECT first_name where id not equal 1
SELECT first_name FROM schema_name.table_name WHERE id != 1;