ECE385H1 Chapter Notes -Foreign Key, Candidate Key, Data Integrity
12 Apr 2013
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Describe the action(s) caused by the actions below. When actions follow from integrity constraints, say why you think the dba speci ed those constraints. Note: in all cases you may assume that a violation of an attribute"s domain will fail (e. g. exceeding the size of varchar(20)): change a sta member"s password. Answer: the deletion of the tuple for the client who is a provider will succeed. Also the corresponding relationships tuple (i. e. , which references to the client tuple) will also be deleted due to the on delete cascade constraint. Any correspoding voucher tuples (those which reference the client tuple) will also be deleted, due to the on delete cascade constraint in voucher: change an existing client"s primary phone number. Answer: the change will always succeed: change a client"s address. Answer: changing a client"s address means to change the addressid value in a client tuple.
