[soci-users] class holder, method T get() always causes exception

[Andy]

My code:
first I run query:
rowset<row> rs = (sql.prepare << "SELECT amount, type, tx_hash, usd_value,
block_time FROM "
<< dbParams.transactionsTabName
<< " WHERE address = '" + hash + "'
AND block_time >= '" << startTimeStr << "'");

next I try:

AddressData DatabaseConnector::GetDataFromRowset(const rowset<row> &rs)
const {
AddressData data;

for(auto it = rs.begin(); it != rs.end(); ++it)
{
if (it->get_indicator(0) == i_null) {
cerr << "amount is equal null ! \n";
} else if( it->get_indicator(1) == i_null) {
cerr << "type is equal null ! \n";
} else if(it->get_indicator(2) == i_null) {
cerr << "tx_hash is equal null ! \n";
} else if(it->get_indicator(3) == i_null) {
cerr << "usd_value is equal null ! \n";
} else if(it->get_indicator(4) == i_null) {
cerr << "block_time is equal null ! \n";
} else {
string amountstr = it->get<string>(0);
data.mBtcValues.push_back( converter.satoshiToDouble(
it->get<unsigned long long int>(0) ));
data.mType.push_back(atoi(it->get<string>(1).c_str()));
if(it->get<string>(1) == "0")
data.mBtcValues.back() = -data.mBtcValues.back();
data.mTranHashes.push_back( it->get<string>(2) );
data.mUsdValues.push_back( it->get<double>(3) );
data.mTimestamps.push_back( it->get<tm>(4) );
}
}

return data;
}

even string amountstr = it->get<string>(0) causes exception
it->get_indicator(0)is not null
error is in :
class holder
{
public:
holder() {}
virtual ~holder() {}

template<typename T>
T get()
{
type_holder<T>* p = dynamic_cast<type_holder<T> *>(this);
if (p)
{
return p->template value<T>();
}
else
{
throw std::bad_cast();
}
}