mysqlquery.cpp

C++连接一写常用数据库的接口

   _mysqlCurrentRow(0),
   _recordValues(NULL),
   _numRecordValues(0),
   _fieldInformation(NULL),
   _numFieldInformation(0),
   _parameters(NULL),
   _numParameters(0)
{

}  // MysqlQuery::MysqlQuery



//------------------------------------------------------------------------------
// MysqlQuery::~MysqlQuery
//------------------------------------------------------------------------------
MysqlQuery::~MysqlQuery()
{   
   // If there is still a transaction, rollback
   if (_isTransaction)
      rollback();
   
   //Make sure any stored query results are freed.
   if (__mysql_res__ != NULL)
   {
      mysql_free_result(__mysql_res__);
      __mysql_res__ = NULL;
   }

   // Free any parameters
   _freeCollection(BIND_PARAMETERS);
   
   // Free the current field values
   _freeCollection(FIELD_VALUES);
  
   // Clear any previouse field information.
   _freeCollection(FIELD_INFORMATION);

   // Release this connection from the parent connection object.
   _parentConnection->releaseQueryConnection(this);
}  // MysqlQuery::~MysqlQuery


//------------------------------------------------------------------------------
// MysqlQuery::clearBindParams
//------------------------------------------------------------------------------
void 
MysqlQuery::clearBindParams()
{
   // Free all the bind parameters.
   _freeCollection(BIND_PARAMETERS);   
}  // MysqlQuery::clearBindParams


//------------------------------------------------------------------------------
// MysqlQuery::command
//------------------------------------------------------------------------------
void
MysqlQuery::command(
   const string& sqlStatement)
{
   // Clear any bind parameters as we now have a new query
   clearBindParams();
   
   // Call the base query to store a copy of the query.
   BaseQuery::command(sqlStatement);   
} // MysqlQuery::command


//------------------------------------------------------------------------------
// MysqlQuery::bindParam
//------------------------------------------------------------------------------
BaseValue*
MysqlQuery::bindParam(
   const string& paramName)
{
   // Make sure the name has not already been added. If it has, return the instance to it
   for (int i=0; i<_numParameters; i++)
      if (strcasecmp(_parameters[i]->bindName.c_str(), paramName.c_str()) == 0)
         return _parameters[i];

   // Make sure the parameter is present in the quey
   if (!_isBindParameterPresent(paramName))
   {
      string err = "bindParam(): The specified bind parameter, ";
      err += paramName;
      err += ", is not present in the SQL statement: ";
      err += _sqlStatement;      
      throw BindParameterNotPresent(err);
   }
      
   // Add the value to the parameters array.
   _numParameters++;
   _parameters = (MysqlBindParam**)realloc((void*)_parameters, _numParameters * sizeof(MysqlBindParam*));
   _parameters[_numParameters-1] = new MysqlBindParam(paramName);        
   return _parameters[_numParameters-1];   
}  // MysqlQuery::bindParam


//------------------------------------------------------------------------------
// MysqlQuery::execute
//------------------------------------------------------------------------------
void
MysqlQuery::execute()
{
   //Make sure any stored query results are freed.
   if (__mysql_res__ != NULL)
   {
      mysql_free_result(__mysql_res__);
      __mysql_res__ = NULL;
   }

   // Number of rows in the result set is now 0
   _mysqlNumRows = 0;
   _mysqlCurrentRow = 0;
   
   // Clear any previouse field information.
   _freeCollection(FIELD_INFORMATION);
 
   // Free the current field values
   _freeCollection(FIELD_VALUES);

   // IIF there is transaction support enabled then
   //   always make sure there is a transaction that the query is occuring in
   if (_parentConnection->_mysqlOptions.mysqlOptTransaction)
      if (!_isTransaction)
         transBegin();
         
   // Resolve the bind parameters
   string resolvedSqlStatement = _mysqlParseBindParameters(_sqlStatement);

   // Ping the connection to make sure it is still valid.
   _parentConnection->_mysqlPing(_index);

   // Execute the query
   _parentConnection->_mysqlQuery(_index, resolvedSqlStatement);

   // Determine if we have any data or not and get the field structures if we do.
   // Using store result. This should change to be configurable from the config file.
   __mysql_res__ = mysql_store_result(&_parentConnection->_handles[_index]->__mysql__);
   if (__mysql_res__ == NULL)
   {
      // MySQL returned nothing. Is it an error or a DDL or DML statement.
      if (mysql_errno(&_parentConnection->_handles[_index]->__mysql__))  
      {
         string err = "execute(): ";
         err += "SQL statement: ";
         err += _sqlStatement;
         err += ", ";
         err += mysql_error(&_parentConnection->_handles[_index]->__mysql__);
         throw ErrorQuerying(err);
      }

      // Nope, its a DDL or DML statement.
      _fieldCount = 0;
      _eof = true;
   }
   else
   {
      // We have data
      _fieldCount = mysql_num_fields(__mysql_res__);
    
      // Get the field information for this query.
      _mysqlGetFieldsInformation();
      
      // Store the number of rows in the result set.
      _mysqlNumRows = mysql_num_rows(__mysql_res__);
      
      if (!_mysqlNumRows)
         _eof = true;     // No data in result set
      else
         _eof = false;
   }   
}  // MysqlQuery::execute



//------------------------------------------------------------------------------
// MysqlQuery::next
//------------------------------------------------------------------------------
void
MysqlQuery::fetchNext()
{        
   // Do nothing if the we have reached the end of file.
   if (_eof)
      return;
   
   // Get the data. mysql_fetch_row() will advance the cursor and don't need to use mysql_data_seek 
   // mysql_data_seek slows performance on large result sets :( (Thanks to David Wojtowicz for this)   
   _mysqlGetResultSetRow();
   _mysqlCurrentRow++;
   
   // Check if we are at the end of the result set.
   if (_mysqlCurrentRow >= _mysqlNumRows)
      _eof = true;
}  // MysqlQuery::next



//------------------------------------------------------------------------------
// MysqlQuery::transBegin
//------------------------------------------------------------------------------
void
MysqlQuery::transBegin()
{
   // Only allow transactions if they have been enabled
   if (_parentConnection->_mysqlOptions.mysqlOptTransaction)
   {
      // Transaction support enabled
      // Make sure a transaction is not already active
      if (_isTransaction)
         throw TransactionError("transBegin(): "
            "A transaction is already active. Commit or rollback the transaction before creating a new transaction.");
      
      // Ping the connection to make sure it is still valid.
      _parentConnection->_mysqlPing(_index);
      
      string query = "BEGIN";
      if (mysql_real_query(&_parentConnection->_handles[_index]->__mysql__, query.c_str(), query.length()) != 0)
      {
         // Something went wrong while trying to execute the sql statement, so throw an exception.
         string err = "transBegin(): Unable to start transaction";
         err += ", ";
         err += mysql_error(&_parentConnection->_handles[_index]->__mysql__);
         throw TransactionError(err);
      }      
      
   	_isTransaction = true;      
   }
   else
   {
      // Transaction support not enabled
      throw NotImplemented("transBegin(): Transaction support is not enabled. Please enable in .ini file with 'mysql_opt_transaction = yes' entry.");
   }
}  // MysqlQuery::transBegin
   
   


//------------------------------------------------------------------------------
// MysqlQuery::commit
//------------------------------------------------------------------------------
void
MysqlQuery::commit()
{
   // Only allow transactions if they have been enabled
   if (_parentConnection->_mysqlOptions.mysqlOptTransaction)
   {
      // Transaction support enabled
      // Make sure a transaction is active
      if (!_isTransaction)
         throw TransactionError("commit(): "
            "A transaction is not active. Create a transaction before calling commit.");

      // Ping the connection to make sure it is still valid.
      _parentConnection->_mysqlPing(_index);
      
      string query = "COMMIT";
      if (mysql_real_query(&_parentConnection->_handles[_index]->__mysql__, query.c_str(), query.length()) != 0)
      {
         // Something went wrong while trying to execute the sql statement, so throw an exception.
         string err = "commit(): Unable to commit the transaction";
         err += ", ";
         err += mysql_error(&_parentConnection->_handles[_index]->__mysql__);
         throw TransactionError(err);
      }      

      _isTransaction = false;
   }
   else
   {
      // Transaction support not enabled
      throw NotImplemented("commit(): Transaction support is not enabled. Please enable in .ini file with 'mysql_opt_transaction = yes' entry.");
   }
}  // MysqlQuery::commit
   
   

//------------------------------------------------------------------------------
// MysqlQuery::rollback
//------------------------------------------------------------------------------
void
MysqlQuery::rollback()
{
   // Only allow transactions if they have been enabled
   if (_parentConnection->_mysqlOptions.mysqlOptTransaction)
   {
      // Transaction support enabled
      // Make sure a transaction is active
      if (!_isTransaction)
         throw TransactionError("rollback(): "
            "A transaction is not active. Create a transaction before calling commit.");
      
      // Ping the connection to make sure it is still valid.
      _parentConnection->_mysqlPing(_index);
      
      string query = "ROLLBACK";
      if (mysql_real_query(&_parentConnection->_handles[_index]->__mysql__, query.c_str(), query.length()) != 0)
      {
         // Something went wrong while trying to execute the sql statement, so throw an exception.
         string err = "commit(): Unable to rollback the transaction";
         err += ", ";
         err += mysql_error(&_parentConnection->_handles[_index]->__mysql__);
         throw TransactionError(err);
      }
      
   	_isTransaction = false;      
   }
   else
   {
      // Transaction support not enabled
      throw NotImplemented("rollback(): Transaction support is not enabled. Please enable in .ini file with 'mysql_opt_transaction = yes' entry.");
   }   
}  // MysqlQuery::rollback



//------------------------------------------------------------------------------
// MysqlQuery::getFieldInfoByColumn
//------------------------------------------------------------------------------
BaseFieldDescription*
MysqlQuery::getFieldInfoByColumn(
   int index)
{
   // Make sure the index is in range.
   if (index < 0 || index >= _numFieldInformation)
      throw IndexOutOfRange("getFieldInfoByColumn(): The field index is out of range for the current result set");

   return _fieldInformation[index];
}  // MysqlQuery::getFieldInfoByColumn


//------------------------------------------------------------------------------
// MysqlQuery::getFieldInfoByName
//------------------------------------------------------------------------------
BaseFieldDescription*
MysqlQuery::getFieldInfoByName(
   const string& fieldName)
{
   // Try and find the field name
   for (int i=0; i<_numFieldInformation; i++)
      if (strcasecmp(_fieldInformation[i]->name().c_str(), fieldName.c_str()) == 0)
         return _fieldInformation[i];

   throw NameNotFound("getFieldInfoByName(): The field name was not found for the current result set.");
}  // MysqlQuery::getFieldInfoByName


//------------------------------------------------------------------------------
// MysqlQuery::getFieldByColumn
//------------------------------------------------------------------------------
BaseValue*
MysqlQuery::getFieldByColumn(
   int index)
{
   // Make sure the index is in range.
   if (index < 0 || index >= _numRecordValues)
   {
      throw IndexOutOfRange("getFieldByColumn(): The field index is out of range for the current result set");
   }

   return _recordValues[index];
}  // MysqlQuery::getFieldByColumn
   

//------------------------------------------------------------------------------
// MysqlQuery::getFieldByName
//------------------------------------------------------------------------------
BaseValue*
MysqlQuery::getFieldByName(
   const string& fieldName)
{
   // Try and find the field name
   for (int i=0; i<_numRecordValues; i++)
      if (strcasecmp(_recordValues[i]->name().c_str(), fieldName.c_str()) == 0)
         return _recordValues[i];

   throw NameNotFound("getFieldByName(): The field name was not found for the current result set.");   
}  // MysqlQuery::getFieldByName