Unit

-- Basic unit values
SELECT '100 m'::unit AS length;        -- 100 meters
SELECT '50 kg'::unit AS mass;          -- 50 kilograms
SELECT '10 m/s'::unit AS velocity;     -- 10 meters per second
SELECT '9.81 m/s^2'::unit AS gravity;  -- 9.81 meters per second squared

-- Convert meters to kilometers
SELECT '1000 m'::unit @ 'km' AS kilometers;  -- Returns: 1 km

-- Convert kilometers to meters
SELECT '1 km'::unit @ 'm' AS meters;         -- Returns: 1000 m

-- Addition and subtraction (must have same dimensions)
SELECT '1 km'::unit + '100 m'::unit AS total_distance;    -- Returns: 1.1 km
SELECT '1 hour'::unit - '30 min'::unit AS time_diff;      -- Returns: 30 min

-- Multiplication
SELECT '10 m'::unit * '5 m'::unit AS area;               -- Returns: 50 m²
SELECT '50 kg'::unit * '9.81 m/s^2'::unit AS force;      -- Returns: 490.5 kg⋅m/s²

-- Division
SELECT '100 m'::unit / '10 s'::unit AS speed;            -- Returns: 10 m/s
SELECT '500 m'::unit / '2 m'::unit AS ratio;             -- Returns: 250 (dimensionless)

-- Create a table with unit columns
CREATE TABLE physical_measurements (
    tenant_id uuid,
    id int,
    distance unit,
    mass unit,
    temperature unit,
    PRIMARY KEY (tenant_id, id)
);

-- Insert measurements
INSERT INTO physical_measurements (tenant_id, id, distance, mass, temperature) VALUES
    ('11111111-1111-1111-1111-111111111111', 1, '100 m', '75 kg', '37 degC'),
    ('11111111-1111-1111-1111-111111111111', 2, '2.5 km', '80 kg', '36.5 degC');

-- Query with conversions
SELECT
    distance @ 'm' AS distance_meters,
    mass @ 'g' AS mass_grams,
    temperature @ 'degF' AS temp_fahrenheit
FROM physical_measurements;

-- These will raise errors
SELECT '1 m'::unit + '1 kg'::unit;          -- Error: dimension mismatch
SELECT '100 m^2'::unit @ 'm';              -- Error: dimension mismatch
SELECT '10 m/s'::unit * '5 kg/m'::unit;     -- Works: results in 50 kg/s