Types & casting

The core types, and converting between them.

Pick the right type

Postgres is strongly typed. The everyday types:

int / bigint — whole numbers; numeric(p,s) — exact decimals (money!); real/double precision — floats
text / varchar(n) — strings
boolean — true/false
date, timestamp, timestamptz, interval — time
uuid, json/jsonb, arrays — covered next

Convert with ::type (or CAST(x AS type)):

SELECT '42'::int, 3.7::int, 'true'::boolean, now()::date;

Casting is not truncation: 14.99::int is 15, not 14. And the last row is why money is numeric — the drift is in the binary representation itself, so no amount of rounding at the end recovers the lost cents.