@Override
    public BigInteger getValue(ResultSet rs, int startIndex) throws SQLException {
        BigDecimal bd = rs.getBigDecimal(startIndex);
        return bd != null ? bd.toBigInteger() : null;
    }
{@code BigIntegerType} maps BigInteger to BigDecimal on the JDBC level

@author tiwe
querydsl-sql/src/main/java/com/querydsl/sql/types/BigIntegerType.java