[Database] Fix multi-statement error reporting (#3425)

common/mysql_request_result.h

@@ -33,30 +33,42 @@ private:
 	uint32 m_LastInsertedID;
 	uint32 m_ErrorNumber;
 
+	std::string m_error_message;
 
 public:
 
 	MySQLRequestResult(MYSQL_RES* result, uint32 rowsAffected = 0, uint32 rowCount = 0, uint32 columnCount = 0, uint32 lastInsertedID = 0, uint32 errorNumber = 0, char *errorBuffer = nullptr);
-	MySQLRequestResult();	
+	MySQLRequestResult();
 	MySQLRequestResult(MySQLRequestResult&& moveItem);
 	~MySQLRequestResult();
 
 	MySQLRequestResult& operator=(MySQLRequestResult&& other);
 
 	bool Success() const { return m_Success;}
-	std::string ErrorMessage() const {return m_ErrorBuffer ? std::string(m_ErrorBuffer) : std::string("");}
+	std::string ErrorMessage() const {
+		if (!m_error_message.empty()) {
+			return m_error_message;
+		}
+
+		return m_ErrorBuffer ? std::string(m_ErrorBuffer) : std::string("");
+	}
 	uint32 ErrorNumber() const {return m_ErrorNumber;}
 	uint32 RowsAffected() const {return m_RowsAffected;}
 	uint32 RowCount() const {return m_RowCount;}
 	uint32 ColumnCount() const {return m_ColumnCount;}
 	uint32 LastInsertedID() const {return m_LastInsertedID;}
 	// default to 0 index since we mostly use it that way anyways.
-	uint32 LengthOfColumn(int columnIndex = 0); 
+	uint32 LengthOfColumn(int columnIndex = 0);
 	const std::string FieldName(int columnIndex);
 
 	MySQLRequestRow& begin() { return m_CurrentRow; }
 	MySQLRequestRow& end() { return m_OneBeyondRow; }
 
+	uint32 GetErrorNumber() const;
+	void SetErrorNumber(uint32 m_error_number);
+	const std::string &GetErrorMessage() const;
+	void SetErrorMessage(const std::string &m_error_message);
+
 private:
 	void FreeInternals();
 	void ZeroOut();