#include <fstream>
#include <iostream>
#include <vector>
using namespace std;
class db_engine {
vector<string> cmdList;
//vector<vector<string>> table;
public:
db_engine();
void createCmd(string tableName, vector<string> attributes, vector<string> pkeys);
//void openCmd();
void saveCmd();
void showCmd(string tableName);
void insertQuery(string tableName, vector<string> t);
void deleteQuery();
void selectQuery();
void projectQuery();
void productQuery();
bool unionComp();
};