PostgreSQL 9.2 tstzrange null/infinity CONSTRAINT CHECK

constraintdata integritydatabase-designpostgresqlpostgresql-9.2

I'd like to limit a PostgreSQL 9.2 tstzrange to valid dates at both ends. No NULLs nor 'infinity'.

Various revisions of this SQL isn't constraining '-/+infinity' input:

CREATE TABLE bill
(
  id serial NOT NULL,
  created_at timestamp with time zone NOT NULL DEFAULT now(),
  period tstzrange NOT NULL,
  -- other columns
  CONSTRAINT bill_pk PRIMARY KEY (id),
  CONSTRAINT bill_period_lower_not_null_ck CHECK (lower(period) IS NOT NULL),
  CONSTRAINT bill_period_upper_not_null_ck CHECK (upper(period) IS NOT NULL),
  CONSTRAINT bill_period_lower_not_infinity_ck CHECK (lower_inf(period) IS FALSE),
  CONSTRAINT bill_period_upper_not_infinity_ck CHECK (upper_inf(period) IS FALSE)
);


INSERT INTO bill (period) VALUES (tstzrange (NULL, NULL));
INSERT INTO bill (period) VALUES (tstzrange ('2000-05-10', '2015-02-22');
INSERT INTO bill (period) VALUES (tstzrange ('2000-05-10', now());
INSERT INTO bill (period) VALUES (tstzrange ('infinity', now());
INSERT INTO bill (period) VALUES (tstzrange ('-infinity', now());
INSERT INTO bill (period) VALUES (tstzrange (now(), 'infinity');


psql (9.2.3)
Type "help" for help.

test_1=> SELECT id, period FROM bill;
 id |                           period
----+------------------------------------------------------------
  1 | ["2000-05-10 00:00:00+01","2015-02-22 00:00:00+00")
  2 | ["2000-05-10 00:00:00+01","2013-10-16 13:20:01.793803+01")
  4 | [-infinity,"2013-10-16 13:20:18.993038+01")
  5 | ["2013-10-16 13:21:14.208279+01",infinity)
(4 rows)

Changing the *_inf(period) IS FALSE checks to TRUE rejects valid dates.

Range functions in the manual

Thoughts?

Best Answer

The simple checks work as desired:

CHECK ( lower(period) > '-infinity' )

and

CHECK ( upper(period) < 'infinity' )

Therefore, you can have:

CREATE TABLE bill
(
  id serial NOT NULL,
  created_at timestamp with time zone NOT NULL DEFAULT now(),
  period tstzrange NOT NULL,
  -- other columns
  CONSTRAINT bill_pk PRIMARY KEY (id),
  CONSTRAINT bill_period_lower_not_null_ck CHECK (lower(period) IS NOT NULL),
  CONSTRAINT bill_period_upper_not_null_ck CHECK (upper(period) IS NOT NULL),
  CONSTRAINT bill_period_lower_not_infinity_ck 
    CHECK ( lower(period) > '-infinity' ),
  CONSTRAINT bill_period_upper_not_infinity_ck 
    CHECK ( upper(period) < 'infinity' )
);

Related Solutions

Mysql – Two nullable columns one required to have value

A version of JD Schmidt's answer, but without the awkwardness of an extra column:

CREATE TABLE foo (
  FieldA INT,
  FieldB INT
);

DELIMITER //
CREATE TRIGGER InsertFieldABNotNull BEFORE INSERT ON foo
FOR EACH ROW BEGIN
  IF (NEW.FieldA IS NULL AND NEW.FieldB IS NULL) THEN
    SIGNAL SQLSTATE '45000'
    SET MESSAGE_TEXT = '\'FieldA\' and \'FieldB\' cannot both be null';
  END IF;
END//
CREATE TRIGGER UpdateFieldABNotNull BEFORE UPDATE ON foo
FOR EACH ROW BEGIN
  IF (NEW.FieldA IS NULL AND NEW.FieldB IS NULL) THEN
    SIGNAL SQLSTATE '45000'
    SET MESSAGE_TEXT = '\'FieldA\' and \'FieldB\' cannot both be null';
  END IF;
END//
DELIMITER ;

INSERT INTO foo (FieldA, FieldB) VALUES (NULL, 10); -- OK
INSERT INTO foo (FieldA, FieldB) VALUES (10, NULL); -- OK
INSERT INTO foo (FieldA, FieldB) VALUES (NULL, NULL); -- gives error
UPDATE foo SET FieldA = NULL; -- gives error

PostgreSQL 9.2 number of days in a tstzrange

There are probably better ways to do this, but here are a few functions to return days or intervals from a tstzrange/tsrange input parameter.

CREATE OR REPLACE FUNCTION extract_interval(TSTZRANGE) RETURNS interval AS
$func$
select upper($1) - lower($1);
$func$ LANGUAGE sql STABLE;

CREATE OR REPLACE FUNCTION extract_interval(TSRANGE) RETURNS interval AS
$func$
select upper($1) - lower($1);
$func$ LANGUAGE sql STABLE;


CREATE OR REPLACE FUNCTION extract_days(TSTZRANGE) RETURNS integer AS
$func$
select (date_trunc('day',upper($1))::DATE - date_trunc('day',lower($1))::DATE) + 1;
$func$ LANGUAGE sql;

CREATE OR REPLACE FUNCTION extract_days(TSRANGE) RETURNS integer AS
$func$
select (date_trunc('day',upper($1))::DATE - date_trunc('day',lower($1))::DATE) + 1;
$func$ LANGUAGE sql;


WITH tzr AS (SELECT tstzrange('2013-10-01 10:00-07', '2013-10-03 05:15-07') AS dttz, tstzrange('2013-10-01 10:00', '2013-10-03 05:15') AS dt)
SELECT  extract_interval(dttz) as interval_with_tz,
        extract_interval(dt) as interval_no_tz,
        extract_days(dttz) as days_with_tz,
        extract_days(dt) as days_no_tz
FROM tzr;

                      tstzrange                      | interval_with_tz | interval_no_tz | days_with_tz | days_no_tz 
-----------------------------------------------------+------------------+----------------+--------------+------------
 ["2013-10-01 07:00:00-07","2013-10-01 07:15:00-07") | 00:15:00         | 00:15:00       |            1 |          1

Edit: I have put up these functions on the Postgresql Wiki so that others can use or edit them if more efficient versions are developed. https://wiki.postgresql.org/wiki/Extract_days_from_range_type

Best Answer

Related Solutions

Mysql – Two nullable columns one required to have value

PostgreSQL 9.2 number of days in a tstzrange

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