The following method may be used to avoid Cartesian products when you create a join.
               	 
            
 
            	 
             
               		
               -  Usually you should have at least 
                  		  t-1 join conditions for a join between 
                  		  t tables.
                  		
               
-  If there are multi-column primary keys on a referenced table, there should be as many join conditions between the child table
                  and the referenced table as there are columns in the primary key of the referenced table. 
                  		
               
-  Turn on the 
                  		  Prohibit Cartesian Products option.