Database Modeling & Design Fourth Edition- P44 doc

... Logical Database Design 9.9 Design Compliance Checking With all complex designs, and particularly when multiple designers are involved, it can be very hard to maintain the integrity of the system design. ... software architects and designers grapple with this by defining design guidelines and rules. These are sometimes called design patterns” and “anti-patterns.” A design pattern...

Ngày tải lên: 05/07/2014, 05:20

... available to help design the most efficient databases. This book is devoted to the logical design methodologies and tools most popular for relational databases today. Physical design methodologies ... Tools for Logical Database Design 187 9.1 Introduction to the CASE Tools 188 9.2 Key Capabilities to Watch For 191 9.3 The Basics 192 9.4 Generating a Database from a Design 196 9....

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... concepts that can be applied to the conceptual data modeling phase of the database life cycle. In Section 2.1, we will look at the simple level of ER modeling described in the original work by Chen ... all occurrences of that entity depend on an associated (strong) entity for their existence in the database. For example, in Figure 2.1, the weak entity Employee-job-history is related to...

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... models with different end user views was severely limited until it could be extended to include database abstraction concepts such as generalization. The gen- eralization relationship specifies ... three entities attached to a single relation- ship diamond, and the connectivity of each entity is designated as either “one” or “many.” An entity in a ternary relationship is considered to be “o...

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... resulting table. The two key attributes are taken from the same domain but are given different names to designate their unique use. The one-to-many relationship requires a foreign key in the resulting

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... diagram or by taking the composite of all attributes as the default key. Note that the primary key designation implies that the attribute is not null or unique. It is important to note, however, ... keys of the associated entities as its composite primary key; the components of that key are also designated as foreign keys in SQL. A ter- nary or higher-level n-ary relationship is transformed ....

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... A -> B. In the preceding example from Figure 6.2, let us assume we are given the following functional dependencies for the table report: report: report_no -> editor, dept_no dept_no -> ... a transitive FD in report is the following: report_no -> dept_no dept_no -> dept_name Therefore we can derive the FD (report_no -> dept_name), since dept_name is transitively dependent ......

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... is to find the data somewhere outside the database and insert it back into the database. All three of these anomalies represent prob- lems to database designers, but the delete anomaly is by far ... 6.3. The FDs for these 2NF tables are: report1: report_no -> editor, dept_no dept_no -> dept_name, dept_addr report2: author_id -> author_name, author_addr report3: report_no, author...

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... with MVDs A ->> B and CD ->> EF. The first decomposition of R is into two tables R1(A,B) and R2(A,C,D,E,F) by applying the MVD A ->> B and its complement A->>CDEF. Table ... CD ->> EF and its complement CD ->> A. Both R21 and R22 are now 4NF. If we had applied the MVD complement rule in the opposite order, using CD ->> EF and its complement CD ->&g...

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... growth should be estimated, as each will have significant effect on the later stages of database design. 7.1.1 Design Problems 1. Using the information given and, in particular, the five assertions, derive ... relationship. a. one-to-one-to-one => three overlapping composite keys, at least BCNF b. one-to-one-to-many => two overlapping composite keys, at least BCNF c. one-to-many-t...

Ngày tải lên: 05/07/2014, 05:20