Support CHECK constraints

[mpscholten]

No description provided.

[hendi]

This looks like its limited to basic inequality checks. Checks for equality =, NULL testing (IS NULL / IS NOT NULL) and comparisons (> / <) fail. Logic operations are also not supported.

Example that does work in Postgres, but not in IHP:

CREATE TYPE property_type AS ENUM ('haus_buy', 'haus_rent');

CREATE TABLE properties (
    id UUID DEFAULT uuid_generate_v4() PRIMARY KEY NOT NULL,
    property_type property_type NOT NULL,
    area_living INT NOT NULL,
    area_garden INT,
    rent_monthly INT DEFAULT NULL,
    price INT DEFAULT NULL
);

ALTER TABLE properties ADD CONSTRAINT foobar CHECK (
    (property_type = 'haus_buy'
        AND area_garden IS NOT NULL 
        AND rent_monthly IS NULL
    )
    OR (property_type = 'haus_rent'
        AND rent_monthly IS NOT NULL
        AND price IS NULL
    )
);

[mpscholten]

@hendi fixed via 7cbfb1f