Создание функций

CREATE TABLE room_classes
(
class NUMERIC(1) CHECK (class IN (1, 2, 3, 4, 5)) CONSTRAINT pk_class PRIMARY KEY,
cost  NUMERIC(9) NOT NULL
);
 
CREATE TABLE rooms
(
r_id NUMERIC(4) UNIQUE CONSTRAINT pk_r_id PRIMARY KEY,
r_class NUMERIC(1) NOT NULL REFERENCES room_classes(class),
r_seats_number NUMERIC(1) NOT NULL
);
 
CREATE TABLE services
(
s_name VARCHAR(30) CONSTRAINT pk_s_name PRIMARY KEY,
s_description VARCHAR(100) NOT NULL,
s_cost NUMERIC(7) NOT NULL
);
 
CREATE TABLE guests
(
g_passport CHAR(10) NOT NULL,
g_check_in_date DATE NOT NULL,
g_occupied_room NUMERIC(4) NOT NULL REFERENCES rooms(r_id),
g_name VARCHAR(40) NOT NULL,
g_sex CHAR NOT NULL CHECK (g_sex IN ('м', 'ж')) DEFAULT 'м',
g_organization VARCHAR(40),
g_departure_date DATE,
g_sign NUMERIC(1) NOT NULL CHECK (g_sign IN (0, 1, 2)),
CONSTRAINT pk_guest PRIMARY KEY(g_passport, g_check_in_date)
);
 
CREATE TABLE provided_services
(
pr_pass CHAR(10),
pr_date DATE,
FOREIGN KEY(pr_pass, pr_date) REFERENCES guests(g_passport, g_check_in_date),
pr_service VARCHAR(30) REFERENCES services(s_name),
pr_quantity NUMERIC(1) NOT NULL,
pr_cost NUMERIC(7) NOT NULL,
pr_provision_date DATE
);

CREATE OR REPLACE FUNCTION db."USR_BY_HID"(IN hid BOOLEAN)
  RETURNS TABLE(uid INTEGER, uname text) AS
$BODY$
BEGIN
RETURN QUERY
    SELECT "UID", "UFIRSTNAME" || ' ' || 
        LEFT("USECONDNAME",1) || '. ' || 
        LEFT("UTHIRDNAME",1) || '.' AS UNAME
    FROM db."TBLUSER"
    WHERE "UISHIDEN"=hid;
"uid"=0;
"uname"='Все';
END
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100
  ROWS 1000;
ALTER FUNCTION db."USR_BY_HID"(BOOLEAN)
  OWNER TO postgres;

BEGIN
RETURN QUERY
SELECT "UID", "UFIRSTNAME" || ' ' ||
LEFT("USECONDNAME",1) || '. ' ||
LEFT("UTHIRDNAME",1) || '.' AS UNAME
FROM db."TBLUSER"
WHERE "UISHIDEN"=hid
UNION ALL
SELECT 0, 'Все';
END