-- this is an example

group: testgroup
event = {
	eid:number, ename:string, ecity:string
	1, event1, city1
	2, event2, city1
	3, event3, city2
	4, event4, city2
	5, event5, city3
	6, event6, city3
	7, event7, city3
}

registration = {
	cid:number, eid:number
	1, 1
	1, 2
	2, 3
	2, 4
	4, 6
	4, 3
	4, 7
}

customer = {
  cid:number, cname:string, ccity:string
	1, customer1, city1
	2, customer2, city2
	3, customer3, city3
	4, customer4, city2
}