Because contour lines represent elevation and you can't have two different elevations at the same point
By definition, a pothole is a structure mostly located at the surface of roads and highways wherein it is usually characterised by having deep crevices which are primarily caused by extreme soil erosion or the presence of water in the area. In addition, these potholes greatly affect the transportation system of South Africa because the flow of traffic will be interrupted.
Packaged software is a compilation of programs which are grouped together in order to provide publicly with different tools in the same group.
Custom software is a specific program that are advanced for a goal in a department or in a company.
Answer:
Changing the customer number on a record in the Orders table to a number that does not match a customer number in the customer table would violate referential integrity.
If deletes do not cascade, deleting a customer that has orders would violate referential integrity.
If deletes cascade, customer can be deleted and all orders for that customer will automatically be deleted.
