BEGIN;

CREATE TABLE languages (
--  name         type       constraints
    id           BIGSERIAL  PRIMARY KEY,
    code         VARCHAR(2) NOT NULL,
    english_name VARCHAR    NOT NULL,
    self_name    VARCHAR    NOT NULL,

--  CONSTRAINT name                      CHECK (condition)
    CONSTRAINT code_is_language_code     CHECK (is_language_code(code)),
    CONSTRAINT english_name_is_sane_text CHECK (is_sane_text(english_name)),
    CONSTRAINT self_name_is_sane_text    CHECK (is_sane_text(self_name))
);

CREATE UNIQUE INDEX languages_code ON languages (code);
CREATE UNIQUE INDEX languages_english_name ON languages (english_name);

INSERT INTO languages (code, english_name, self_name) VALUES
    ('en', 'English',  'English'),
    ('ru', 'Russian',  'Русский'),
    ('pl', 'Polish',   'Polski'),
    ('es', 'Spanish',  'Español'),
    ('ka', 'Georgian', 'ქართული');

COMMIT;