diff --git a/DBEngine.cpp b/DBEngine.cpp
index d028aea..a10368c 100755
--- a/DBEngine.cpp
+++ b/DBEngine.cpp
@@ -27,6 +27,16 @@ void DBEngine::createTable(Relation r){
 vector<Relation> DBEngine::getRelations(){ 
 	return tables; 
 }
+
+//To check if a relation name is already used.
+bool DBEngine::isRelation(string n){
+	for(int i = 0; i < tables.size(); i++){
+		if (tables[i].getTableName() == n){
+			return true;
+		}
+	}
+	return false;
+}
 	
 Relation& DBEngine::getTableFromName(string n){
 	for(int i = 0; i < tables.size(); i++){
diff --git a/Parserv2.cpp b/Parserv2.cpp
deleted file mode 100755
index cb848f3..0000000
--- a/Parserv2.cpp
+++ /dev/null
@@ -1,196 +0,0 @@
-#include <string>
-#include <iostream> 
-#include <sstream>
-#include <vector>
-#include <string>
-
-using namespace std;
-
-
-vector<string> tokenize(string ss)
-{
-	string tempString;
-	stringstream lineStream(ss);
-	vector<string> output;
-	
-	while (lineStream >> tempString)
-	{
-		output.push_back(tempString);
-	}
-	
-	//testing---------------
-	cout<<"TokenList: ";
-	
-	for (int i = 0; i <output.size(); ++i)
-	{
-		cout<<output[i]<<"  ";
-	}
-	//----------------------
-	
-	return output;
-	
-}
-
-void displayTokenList(vector<string> input)
-{
-	cout<<"TokenList: "<<endl;
-	for (int i = 0; i < input.size(); ++i)
-	{
-		cout<<input[i]<<endl;
-	}
-}
-
-
-vector<string> insertCMD(vector<string> input)
-{
-	//relation name will be the first element of the vector of data returned by this function
-	vector<string> output;
-		
-	if (input[0] == "INTO")
-	{
-		input.erase(input.begin());
-		
-		output.push_back(input[0]);		//pushing relation name
-		
-		input.erase(input.begin());
-		
-		if (input[0] == "VALUES" && input[1] == "FROM")
-		{
-			input.erase(input.begin());
-			input.erase(input.begin());
-			
-			
-			if(input[0] == "(")
-			{			
-				input.erase(input.begin());
-				
-				while(input[0] != ")")	//inserting all values to relation
-				//for (int i = 0; i < 2; ++i)
-				{
-					if (input[0] == ",") input.erase(input.begin());
-					
-					output.push_back(input[0]);
-					
-					input.erase(input.begin());
-				}
-				
-				return output;
-				
-			}
-			
-			else cout<<"Syntax error!"<<endl;
-		}
-		else cout<<"Syntax error!"<<endl;
-		
-	}
-	
-	else cout<<"Syntax error!"<<endl;
-	
-}
-
-vector<string> showCMD(vector<string> input)
-{
-	if (input.size() > 3)
-	{
-		cout<<"Syntax error!"<<endl;
-	}
-				
-	cout<<"\nPassing the following arguments to dbEngine: "<<endl;
-	cout << "command :" << input[0] << endl;
-	cout << "relation name / expression: "<< input[1] << endl;	
-	
-	return input;
-}
-
-vector<string> exitCMD(vector<string> input)
-{
-	if (input[1] != ";")
-	{
-		cout<<"ERROR: missing semicolon!"<<endl;
-		return input;
-	}
-	
-	if (input[0] != "EXIT") { 
-		cout<<"Wrong function/syntax error!"<<endl;
-		return input;
-	}
-	
-	cout<<"Passing command: "<< input[0] <<endl;
-	return input;
-}
-
-
-vector<string> createCMD(vector<string> input)
-{
-	if (input[0] != "CREATE") {
-		cout << "Error: create keyword is missing." <<endl;
-		return input;
-	}
-	
-	cout << "\nPassing the following arguments to dbEngine: " << endl;
-	// CREATE TABLE relation-name ( typed-attribute-list ) PRIMARY KEY ( attribute-list )
-	cout << "command :" << input[0] << endl;
-	cout << "argument: " << input[1] << endl;
-	return input;
-}
-
-vector<string> openCMD(vector<string> input){
-	if (input[0] != "OPEN") {
-		cout << "Error: open keyword is missing." <<endl;
-		return input;
-	}
-	
-	cout << "\nPassing the following arguments to dbEngine: " << endl;
-	cout << "command :" << input[0] << endl;
-	cout << "relation: " << input[1] << endl;
-}
-
-vector<string> closeCMD(vector<string> input){
-	if (input[0] != "CLOSE") {
-		cout << "Error: close keyword is missing." <<endl;
-		return input;
-	}
-	
-	cout << "\nPassing the following arguments to dbEngine: " << endl;
-	cout << "command :" << input[0] << endl;
-	cout << "relation: " << input[1] << endl;
-	return input;
-}
-
-vector<string> saveCMD(vector<string> input){
-	if (input[0] != "SAVE") {
-		cout << "Error: save keyword is missing." <<endl;
-		return input;
-	}
-	
-	cout << "\nPassing the following arguments to dbEngine: " << endl;
-	cout << "command :" << input[0] << endl;
-	cout << "relation: " << input[1] << endl;
-	return input;
-}
-
-vector<string> updateCMD(vector<string> input){
-	//UPDATE relation-name SET attribute-name = literal { , attribute-name = literal } WHERE condition 
-}
-
-vector<string> deleteCMD(vector<string> input){
-	//DELETE FROM relation-name WHERE condition
-	if (input[0] != "DELETE") {
-		cout << "Error: save keyword is missing." <<endl;
-		return input;
-	}
-	
-	cout << "\nPassing the following arguments to dbEngine: " << endl;
-	cout << "command :" << input[0] << endl;
-	cout << "relation: " << input[2] << endl;
-	cout << "condition: " << input[5] << input[6] << input[7] << endl;
-	
-	return input;
-}
-
-int main () {
-	string s = "DELETE FROM animals WHERE ( age == 12 ) ;";
-	
-	vector<string> listOfTokens = tokenize(s);
-	deleteCMD(listOfTokens);
-}
\ No newline at end of file
diff --git a/Parserv3.h b/Parserv3.h
index d3f7812..0064a9b 100644
--- a/Parserv3.h
+++ b/Parserv3.h
@@ -7,22 +7,22 @@
 using namespace std;
 
 
-class Relation
+class PRelation
 {
 	string name;
 	
 	public: 
-		Relation()
+		PRelation()
 		{
-			name = NULL;
+			name = "~";
 		}
 		
-		Relation(string str)
+		PRelation(string str)
 		{
 			name = str;
 		}
 		
-		void setRelation(string str)
+		void setPRelation(string str)
 		{
 			name = str;
 		}	
@@ -32,117 +32,140 @@ class Relation
 		}
 };
 
-class Attribute
+class PAttribute
 {
 	string name;
+	string type;
+	string size;
 	
 	public:
-		Attribute()
+		PAttribute()
 		{
-			name = NULL;
+			name = "~";
+			type = "~";
+			size = "~";
 		}
 		
-		Attribute(string str)
+		PAttribute(string str, string t)
+		{
+			name = str;
+			type = t;
+			size = "~";
+		}
+		
+		PAttribute(string str, string t, string s)
+		{
+			name = str;
+			type = t;
+			size = s;
+		}
+		
+		void setPAttributeName(string str)
 		{
 			name = str;
 		}
 		
-		void setAttribute(string str)
+		void setPAttributeType(string t)
 		{
-			name = str;
+			type = t;
 		}
 		
-		string getAttribute()
+		void setPAttributeSize(string s)
+		{
+			size = s;
+		}
+		
+		string getPAttribute()
 		{
 			return name;
 		}
 };
 
-class Union
+class PUnion
 {
 	string Un1;
 	string Un2;
 	
 	public:
-		Union()
+		PUnion()
 		{
-			Un1 = NULL;
-			Un2 = NULL;
+			Un1 = "~";
+			Un2 = "~";
 		}
 		
-		Union (string s1, string s2)
+		PUnion (string s1, string s2)
 		{
 			Un1 = s1;
 			Un2 = s2;
 		}
 		
-		string getUnion()
+		string getPUnion()
 		{
 			return "Union of " + Un1 + " and " + Un2;
 		}
 };
 
-class Product
+class PProduct
 {
 	string Pr1;
 	string Pr2;
 	
 	public:
-		Product()
+		PProduct()
 		{
-			Pr1 = NULL;
-			Pr2 = NULL;
+			Pr1 = "~";
+			Pr2 = "~";
 		}
 		
-		Product(string s1, string s2)
+		PProduct(string s1, string s2)
 		{
 			Pr1 = s1;
 			Pr2 = s2;
 		}
 		
-		string getProduct()
+		string getPProduct()
 		{
 			return "Product of " + Pr1 + " and " + Pr2;
 		}
 };
 
-class Difference
+class PDifference
 {
 	string D1;
 	string D2;
 	
 	public:
-		Difference()
+		PDifference()
 		{
-			D1 = NULL;
-			D2 = NULL;
+			D1 = "~";
+			D2 = "~";
 		}
 		
-		Difference(string s1, string s2)
+		PDifference(string s1, string s2)
 		{
 			D1 = s1;
 			D2 = s2;
 		}
 		
-		string getDifference()
+		string getPDifference()
 		{
 			return "Difference of " + D1 + " and " + D2;
 		}
 };
 
-class Renaming
+class PRenaming
 {
 	string newName;
 	string oldName;
 	
 	public:
-		Renaming()
+		PRenaming()
 		{
-			newName = NULL;
-			oldName = NULL;
+			newName = "~";
+			oldName = "~";
 		}
 		
-		Renaming(string s1, string s2)
+		PRenaming(string s1, string s2)
 		{
 			newName = s1;
 			oldName = s2;
@@ -154,211 +177,217 @@ class Renaming
 		}
 };
 
-class Projection
+class PProjection
 {
 	string newName;
 	string oldName;
 	
 	public:
-		Projection()
+		PProjection()
 		{
-			newName = NULL;
-			oldName = NULL;
+			newName = "~";
+			oldName = "~";
 		}
 		
-		Projection(string s1, string s2)
+		PProjection(string s1, string s2)
 		{
 			newName = s1;
 			oldName = s2;
 		}
 		
-		string doProjection()
+		string doPProjection()
 		{
 			return "Projecting " + oldName + " onto " + newName;
 		}
 };
 
-class Operand
+class POperand
 {
 	string op;
 	
 	public:
 	
-		Operand()
+		POperand()
 		{
-			op = NULL;
+			op = "~";
 		}
 		
-		Operand(string str)
+		POperand(string str)
 		{
 			op = str;
 		}
 		
-		void setOperand(string str)
+		void setPOperand(string str)
 		{
 			op = str;
 		}
 		
-		string getOperand()
+		string getPOperand()
 		{
 			return op;
 		}
 };
 
-class Op
+class POp
 {
 	string op;
 	
 	public: 
-		Op()
+		POp()
 		{
-			op = NULL;
+			op = "~";
 		}
 		
-		Op(string str)
+		POp(string str)
 		{
 			op = str;
 		}
 		
-		void setOp(string str)
+		void setPOp(string str)
 		{
 			op = str;
 		}
 		
-		string getOp()
+		string getPOp()
 		{
 			return op;
 		}
 };
 
-class Comparison
+class PComparison
 {
-	Op op;
-	Operand operand1;
-	Operand operand2;
+	POp op;
+	POperand operand1;
+	POperand operand2;
 	
 	public:
-		Comparison()
+		PComparison()
 		{
-			op = NULL;
-			operand1 = NULL;
-			operand2 = NULL;
+			op.setPOp("~");
+			operand1.setPOperand("~");
+			operand2.setPOperand("~");
 		}
 		
-		Comparison(string str1, string str2, string str3)
+		PComparison(string str1, string str2, string str3)
 		{
-			operand1.setOperand(str1);
-			op.setOp(str2);
-			operand2.setOperand(str3);
+			operand1.setPOperand(str1);
+			op.setPOp(str2);
+			operand2.setPOperand(str3);
 		}
 		
-		void setComparison(string str1, string str2, string str3)
+		void setPComparison(string str1, string str2, string str3)
 		{
-			operand1.setOperand(str1);
-			op.setOp(str2);
-			operand2.setOperand(str3);
+			operand1.setPOperand(str1);
+			op.setPOp(str2);
+			operand2.setPOperand(str3);
 		}
 		
-		string getComparison()
+		string getPComparison()
 		{
-			return operand1.getOperand() + " " + op.getOp() + " " + operand2.getOperand();
+			return operand1.getPOperand() + " " + op.getPOp() + " " + operand2.getPOperand();
 		}
 };
 
-class Conjunction
+class PConjunction
 {
 	string conj;
 	public:
-		Conjunction()
+		PConjunction()
 		{
-			conj = NULL;
+			conj = "~";
 		}
 		
-		Conjunction(string str)
+		PConjunction(string str)
 		{
 			conj = str;
 		}
 		
-		void setConjunction(string str)
+		void setPConjunction(string str)
 		{
 			conj = str;
 		}
 		
-		string getConjunction()
+		string getPConjunction()
 		{
 			return conj;
 		}
 };
 
-class Condition
+class PCondition
 {
 	string cond;
 	public:
 	
-		Condition()
+		PCondition()
 		{
-			cond = NULL;
+			cond = "~";
 		}
 	
-		Condition(string str)
+		PCondition(string str)
 		{
 			cond = str;
 		}
 		
-		void setCondition(string str)
+		void setPCondition(string str)
 		{
 			cond = str;
 		}
 		
-		string getCondition()
+		string getPCondition()
 		{
 			return cond;
 		}
 };
 
-class Selection
+class PSelection
 {
 	string select;
 	public:
-		Selection()
+		PSelection()
 		{
-			select = NULL;
+			select = "~";
 		}
 		
-		Selection(string str)
+		PSelection(string str)
 		{
 			select = str;
 		}
 		
-		string getSelection()
+		string getPSelection()
 		{
 			return select;
 		}
 };
 
-class Expression
+class PExpression
 {
-	string exp;
+	PRelation rel;
+	PSelection sel;
+	PProjection proj;
+	PRenaming ren;
+	PUnion un;
+	PDifference diff;
+	PProduct prod;
+	string temp;
 	
 	public:
 	
-		Expression()
+		PExpression()
 		{
-			exp = NULL;
 		}
 	
-		Expression(string str)
+		PExpression(string str)
 		{
-			exp = str;
+			temp = str;
 		}
 		
-		void setExpression(string str)
+		void setPExpression(string str)
 		{
-			exp = str;
+			temp = str;
 		}
 		
-		string getExpression()
+		string getPExpression()
 		{
-			return exp;
+			return temp;
 		}
 };
diff --git a/Parserv4.cpp b/Parserv4.cpp
index 8d5f17b..f6c0bb4 100644
--- a/Parserv4.cpp
+++ b/Parserv4.cpp
@@ -118,8 +118,8 @@ vector<string> createCMD(vector<string> input)
 		input.erase(input.begin());
 		input.erase(input.begin());
 		
-		Relation r;
-		r.setRelation(input[0]);
+		PRelation r;
+		r.setPRelation(input[0]);
 		
 		input.erase(input.begin());
 		
@@ -127,21 +127,39 @@ vector<string> createCMD(vector<string> input)
 		{			
 			input.erase(input.begin());
 			
-			vector <Expression> e1;
+			//vector <PExpression> e1;
+			
+			vector <PAttribute> a;
 			
 			while(input[0] != ")")	//inserting all values to relation
 			{
+				PAttribute temp;
+				
 				if (input[0] == ",")
 				{
 					input.erase(input.begin());
 				}
 				
-				e1.push_back(input[0]);
+				temp.setPAttributeName(input[0]);
 				
 				input.erase(input.begin());
+				
+				if(input[0] == "INTEGER")
+				{
+					temp.setPAttributeType(input[0]);
+					input.erase(input.begin());
+				}
+				else
+				{
+					temp.setPAttributeType(input[0].substr(0,input[0].find("("))); 
+					temp.setPAttributeSize(input[0].substr(input[0].find("("), input[0].find(")")));
+					input.erase(input.begin());	
+				}
+				
+				a.push_back(temp);
 			}
 			
-			vector <Expression> e2;
+			vector <PAttribute> apk; //save primary keys temp storage
 			
 			if(input[0] == "PRIMARY" && input[1] == "KEY")
 			{
@@ -153,23 +171,21 @@ vector<string> createCMD(vector<string> input)
 				
 					while(input[0] != ")")	//inserting all values to relation
 					{
+						PAttribute temp;
+						
 						if (input[0] == ",")
 						{
 							input.erase(input.begin());
 						}
 						
-						e2.push_back(input[0]);
+						temp.setPAttributeName(input[0]);
+						
+						apk.push_back(temp);
 						
 						input.erase(input.begin());
 					}
 					
-					cout << "Creating a table: " << r.getName() << "\n";
-					cout << "Primary key: ";
-					while(!e2.empty())
-					{
-						cout << e2[0].getExpression() << " ";
-						e2.erase(e2.begin());
-					}
+					
 				
 					return input;
 				}
@@ -190,10 +206,12 @@ vector<string> insertCMD(vector<string> input)
 	{
 		input.erase(input.begin());
 		
-		Relation r(input[0]);
+		PRelation r(input[0]);
 		
 		input.erase(input.begin());
 		
+		vector <string> s;
+		
 		if (input[0] == "VALUES" && input[1] == "FROM")
 		{
 			input.erase(input.begin());
@@ -202,7 +220,11 @@ vector<string> insertCMD(vector<string> input)
 			
 			if(input[0] == "(")
 			{
-				vector <Expression> e;
+				if(input[0].at(0) == '\"')
+				{
+					s.push_back(input[0].substr(1,input[0].find_last_of("\"")));
+				}
+				vector <PExpression> e;
 				input.erase(input.begin());
 				
 				while(input[0] != ")")	//inserting all values to relation
@@ -218,7 +240,7 @@ vector<string> insertCMD(vector<string> input)
 				cout << "Inserting: ";
 				while(!e.empty())
 				{
-					cout << e[0].getExpression() << " ";
+					cout << e[0].getPExpression() << " ";
 					e.erase(e.begin());
 				}
 				cout << "into " << r.getName() << ".\n";
@@ -231,14 +253,14 @@ vector<string> insertCMD(vector<string> input)
 			{
 				input.erase(input.begin());
 				
-				Expression e;
+				PExpression e;
 				
 				while(input[0] != ";")
 				{
-					e.setExpression(e.getExpression() + input[0]);
+					e.setPExpression(e.getPExpression() + input[0]);
 				}
 				
-				cout << "Inserting: " << e.getExpression() << " into " << r.getName() << ".\n";
+				cout << "Inserting: " << e.getPExpression() << " into " << r.getName() << ".\n";
 				
 				return input;
 			}
@@ -263,7 +285,7 @@ vector<string> updateCMD(vector<string> input)
 	{
 		input.erase(input.begin());
 		
-		Relation r(input[0]);
+		PRelation r(input[0]);
 		
 		input.erase(input.begin());
 		
@@ -271,7 +293,7 @@ vector<string> updateCMD(vector<string> input)
 		if(input[0] == "(")
 		{
 			
-			vector <Expression> e;
+			vector <PExpression> e;
 			input.erase(input.begin());
 			
 			while(input[0] != ")")
@@ -282,10 +304,10 @@ vector<string> updateCMD(vector<string> input)
 		
 		if(input[0] == "WHERE")
 		{
-			Condition c;
+			PCondition c;
 			while(input[0] != ";")
 			{
-				c.setCondition(/*c.getCondition +*/ input[0]);
+				c.setPCondition(/*c.getCondition +*/ input[0]);
 			}
 		}
 	}
@@ -301,10 +323,10 @@ vector<string> deleteCMD(vector<string> input)
 		input.erase(input.begin());
 		input.erase(input.begin());
 		
-		Relation r(input[0]);
+		PRelation r(input[0]);
 		if(input[0] == "(")
 		{
-			vector <Expression> e;
+			vector <PExpression> e;
 			input.erase(input.begin());
 			
 			while(input[0] != ")")	
@@ -319,7 +341,7 @@ vector<string> deleteCMD(vector<string> input)
 			cout << "Deleting: ";
 			while(!e.empty())
 			{
-				cout << e[0].getExpression() << " ";
+				cout << e[0].getPExpression() << " ";
 				e.erase(e.begin());
 			}
 			cout << "from " << r.getName() << ".\n";
diff --git a/a.out b/a.out
index 6a77a3d..a09701b 100755
Binary files a/a.out and b/a.out differ