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construct an e-r diagram for a car insurance company whose customers own one or more cars each each car has associated
temporal changes an e-r diagram usually models the state of an enterprise at a point in time suppose we wish to track
in sql foreign key constraints can only reference the primary key attributes of the referenced relation or other
consider the representation of a ternary relationship using binary relationships as described in section 773 and
consider a many-to-one relationship r between entity sets a and b suppose the relation created from r is combined with
show that the following decomposition of the schema r of practice exercise 81 is not a lossless decompositiona b cc d
consider an e-r diagram in which the same entity set appears several times with its attributes repeated in more than
design an e-r diagram for keeping track of the exploits of your favorite sports team you should store the matches
consider a database used to record the marks that students get in different exams of different course offerings
given the three goals of relational database design is there any reason to design a database schema that is in 2nf but
a weak entity set can always be made into a strong entity set by adding to its attributes the primary-key attributes of
suppose the advisor relationship were one-to-one what extra constraints are required on the relation advisor to ensure
testing sql queries to test if a query specified in english has been correctly written in sql the sql query is
sql allows a foreign-key dependency to refer to the same relation as in the following examplehere employeename is a key
sql provides an n-ary operation called coalesce which is defined as follows coalescea1 a2 an returns the first nonnull
some researchers have proposed the concept of marked nulls a marked null perpi is equal to itself but if i ne j then
referential-integrity constraints as defined in this chapter involve exactly two relations consider a database that
write the following inserts deletes or updates in sql using the university schemaa increase the salary of each
consider the insurance database of figure 318 where the primary keys are underlined construct the following sql queries
write the following queries in sql using the university schema we suggest you actually run these queries on a database
consider the bank database of figure 319 where the primary keys are underlined construct the following sql queries for
consider the relational database of figure 320 give an expression in sql for each of the following queriesa give all
consider the bank database of figure 215 give an expression in the relational algebra for each of the following