dmspine64backup/db_engine.cpp

#include "db_engine.h"

using namespace std;

db_engine::db_engine(){
	//
}

//create a new table in memory
//creates a vector 
//DONE
void db_engine::createCmd(string tableName, vector<string> attributes, vector<string> pkeys){
	string output = "";
	output += "CREATE TABLE " + tableName + " (";
	
	vector<string>::iterator it = attributes.begin();
	while (it != attributes.end()){
		if (it == attributes.begin())
			if ((it + 1) != attributes.end())
				output += *it + ",";
			else
				output += *it;
		else
			output+= " " + *it;
		
		++it;
	}
	
	output += ") PRIMARY KEY (";
	
	vector<string>::iterator it2 = pkeys.begin();
	while (it2 != pkeys.end()){
		if (it2 == pkeys.begin())
			if ((it2 + 1) != pkeys.end())
				output += *it2 + ",";
			else
				output += *it2;
		else
			output+= " " + *it2;
		
		++it2;
	}
	
	output += ");";
	
	cout << output;
	//cmdList.push_back(output);
}
	
//open a txt file, parse SQL script, load data in table
//void db_engine::openCmd(){
	//
//}

//should write cmdList to a .txt file
//DONE
void db_engine::saveCmd(){
	ofstream dbCmdFile;
	dbCmdFile.open("dbCmds.txt", ios_base::app);
	
	vector<string>::iterator it = cmdList.begin();
	while (it != cmdList.end()){
		dbCmdFile << *it << "\n";
		++it;
	}
	
	cmdList.clear();
}

//display the database
//DONE
void db_engine::showCmd(string tableName){
	cmdList.push_back("SHOW " + tableName + "");
}

//add a tuple to a table in the memory
//BECCA
void db_engine::insertQuery(){
	//table.push_back();
}

//remove a tuple from a table in the memory
//BECCA
void db_engine::deleteQuery(){
	//
}

//search and return one more tuples from a table in the memory
//WILLIAM
void db_engine::selectQuery(){
	//
}

//return a subset of attributes (columns)
//BRANDON
vector<string> db_engine::projectQuery(vector< vector<string> > table, vector<string> attributes, string query){
	/*
		So basically this is what's going on:
		- Take the table to iterate through, this is the 2D vector (input 1)
		- Take the vector of attributes that pertains to the respective table (input 2)
		- Take a string that will be used for the program to search for in the attributes (input 3)
		- In the attributes vector, iterate through each attribute until the attribute (string) matches the input query
		- For every iterator, have a counter that counts how many attributes are skipped over in the vector until the attribute is found
		- This counter will be used to iterate through each vector (row) in the list, skip over that many attributes, and push that into a result vector
		- Once all vector's elements at the specified attribute are pushed back, return the result vector
	*/
	int counter = 0; //counter for iterating through the attributes, initialized at 0 for reasons
	vector<string> result;

	//Loop through the vector until we have found a string in it that matches the query
	for(int i=0; i < attributes.size(); i++){
		counter++;
		if(attributes[i] == query)
			break;
		else
			continue;
	}
	
	//So let's say we have a 2-D Vector (the table) that contains all of the rows, we iterate through each row
	std::vector< std::vector<int> >::const_iterator row; 
    std::vector<int>::const_iterator col; 

    for (row = table.begin(); row != table.end(); ++row) { 
		//Instead of col != row->end() we have it counter, in order for the program to access the correct data under the correct attribute
		for (col = row->begin(); col != counter; col++) {
			result.push_back(col); //Now we store that row's attribute into the result vector
		}
    }
	
	return result;
}

//each row in the first table is paired with all the rows in the second table
//BRANDON
vector< vector<string> > db_engine::productQuery(vector< vector<string> > table_1, vector< vector<string> > table_2){
	//
}

//true if relations have the same # of attributes and each attribute must be from the same domain
//WILLIAM
bool db_engine::unionComp(){
	return false;
}