public Promise<BigDecimal> total() {
        return Schedulers.async().call(() -> {
            try (Connection c = sql.getConnection()) {
                try (PreparedStatement ps = c.prepareStatement(SELECT_TOTAL.replace("{table}", table))) {
                    try (ResultSet rs = ps.executeQuery()) {
                        if (rs.next()) {
                            return rs.getBigDecimal("total");
                        } else {
                            return BigDecimal.ZERO;
                        }
                    }
                }
            }
        });
    }
Gets the total of all values in the table.

@return the total
helper-sql/src/main/java/me/lucko/helper/sql/util/Uuid2PosDecimalTable.java