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数据库 ER 图练习及答案
DB Modeling Exam Practical
Answer the following questions. 1.
Create an E-R schema for a database system used to manage account
information at a community
bank. The bank has several branches with unique names. A customer may
have one or more accounts in one or more branches. An account must belong
to one and only one branch. Each account is operated on by transactions,
which may be deposits to or withdrawals from some account. The database
keeps track of all the transactions on each account, in addition to the
balance of individual accounts and the assets of individual branches. For
each entity, specify all its attributes, primary key, and alternate key(s).
In your ER schema, be sure to capture the cardinality constraints and
participation constraints of all relationships.
Make reasonable assumptions to complete the specification. Explicitly
state all your assumptions. EVERY construct in your ER schema should be
substantiated by either the specification above or your explicit
assumptions. 2.
The following table stores information about which suppliers can supply
which parts. The table captures
the fact that a part whose name is PartName and whose ID is PartID can
be supplied by suppliers whose names are in SupplierName and whose IDs
are in SupplierID. Note that a part can be supplied by many suppliers,
and a supplier can supply many parts.
CAN_SUPPLY PartID PartName SupplierID SupplierName
1234 1234 2134 Nut Nut Bolt 223 224 223 ProMetal Biscayne ProMetal 3.
1. 2. 3. 4.
Perform the following tasks.
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