postgres

# PostgreSQL (connected) The connection string is in `$POSTGRES_URL` — pass it to `psql` as the first argument. `psql` is preinstalled once the sandbox has been rebuilt for this capability (Environment card). - List tables: `psql "$POSTGRES_URL" -c "\dt"` - Describe a table: `psql "$POSTGRES_URL" -c "\d <table>"` - Run a query: `psql "$POSTGRES_URL" -c "SELECT * FROM <table> LIMIT 20"` - Scriptable output (no headers/formatting, one value): `psql "$POSTGRES_URL" -tAc "SELECT count(*) FROM <table>"` - List databases / schemas: `psql "$POSTGRES_URL" -c "\l"` / `psql "$POSTGRES_URL" -c "\dn"` Notes: this is a read-write connection — the connected role's grants bound what you can do. Wrap risky writes in `BEGIN; … COMMIT;` and prefer a `WHERE` on every `UPDATE`/`DELETE`.