PostgreSQL function: Remove all data from the db's tables, and restart id sequences.

reset_tables.plpgsql

DECLARE
    statements CURSOR FOR
        SELECT tablename FROM pg_tables
        	WHERE schemaname = 'public';
BEGIN
    FOR stmt IN statements LOOP
        EXECUTE 'TRUNCATE TABLE ' || quote_ident(stmt.tablename) || ' CASCADE;';
        EXECUTE 'ALTER SEQUENCE ' || quote_ident('' || stmt.tablename || '_id_seq') || ' RESTART WITH 1';
    END LOOP;
END;
$$ LANGUAGE plpgsql;