making more changes

db_engine.cpp

@@ -0,0 +1,55 @@
+#include "db_engine"
+
+db_engine::db_engine(){
+	//
+}
+
+//create a new table in memory
+db_engine::createCmd(){
+	//
+}
+	
+//open a txt file, parse SQL script, load data in table
+//void db_engine::openCmd(){
+	//
+//}
+
+//save all the commands to the db text file
+void db_engine::saveCmd(){
+	//
+}
+
+//display the table currently stored in memory
+void db_engine::showCmd(){
+	//
+}
+
+//add a tuple to a table in the memory
+void db_engine::insertQuery(){
+	//
+}
+
+//remove a tuple from a table in the memory
+void db_engine::deleteQuery(){
+	//
+}
+
+//search and return one more tuples from a table in the memory
+void db_engine::selectQuery(){
+	//
+}
+
+//return a subset of attributes (columns)
+void db_engine::projectQuery(){
+	//
+}
+
+//each row in the first table is paired with all the rows in the second table
+void db_engine::productQuery(){
+	//
+}
+
+//true if relations have the same # of attributes and each attribute must be from the same domain
+bool db_engine::unionComp(){
+	return false;
+}