TAILIEUCHUNG - Relational Database Design by ER- and EERR-to-Relational Mapping

For each weak entity type W in the ER schema with owner entity type E, create a relation R and include all simple attributes (or simple components of composite attributes) of W as attributes of R. In addition, include as foreign key attributes of R the primary key attribute(s) of the relation(s) that correspond to the owner entity type(s). The primary key of R is the combination of the primary key(s) of the owner(s) and the partial key of the weak entity type W, if any. | Relational Database Design by ER- and EERR-to-Relational Mapping Chapter Outline ER-to-Relational Mapping Algorithm Step 1: Mapping of Regular Entity Types Step 2: Mapping of Weak Entity Types Step 3: Mapping of Binary 1:1 Relation Types Step 4: Mapping of Binary 1:N Relationship Types. Step 5: Mapping of Binary M:N Relationship Types. Step 6: Mapping of Multivalued attributes. Step 7: Mapping of N-ary Relationship Types. Mapping EER Model Constructs to Relations Step 8: Options for Mapping Specialization or Generalization. Step 9: Mapping of Union Types (Categories). ER-to-Relational Mapping Algorithm Step 1: Mapping of Regular Entity Types. For each regular (strong) entity type E in the ER schema, create a relation R that includes all the simple attributes of E. Choose one of the key attributes of E as the primary key for R. If the chosen key of E is composite, the set of simple attributes that form it will together form the primary key of R. Example: We create the relations EMPLOYEE, DEPARTMENT, and PROJECT in the relational schema corresponding to the regular entities in the ER diagram. SSN, DNUMBER, and PNUMBER are the primary keys for the relations EMPLOYEE, DEPARTMENT, and PROJECT as shown. FIGURE The ER conceptual schema diagram for the COMPANY database. FIGURE Result of mapping the COMPANY ER schema into a relational schema. ER-to-Relational Mapping Algorithm (cont) Step 2: Mapping of Weak Entity Types For each weak entity type W in the ER schema with owner entity type E, create a relation R and include all simple attributes (or simple components of composite attributes) of W as attributes of R. In addition, include as foreign key attributes of R the primary key attribute(s) of the relation(s) that correspond to the owner entity type(s). The primary key of R is the combination of the primary key(s) of the owner(s) and the partial key of the weak entity type W, if any. Example: Create the relation DEPENDENT in this step to correspond to the .

• Cơ sở dữ liệu
• Functional Dependencies
• FD constraints
• Spurious Tuples
• Update Anomalies
• Redundant Information
• Primary Keys
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• Math Fundamentals for Informatics
• Discovering functional dependencies
• Relaxed functional dependencies in databases
• Range of relational databases
• Informal Design Guidelines for Relational Databases
• Semantics of the Relation Attributes
• Null Values in Tuples
• Functional dependency
• Conditional functional dependency
• Association rule
• Data dependencies
• Unified hierarchy for FDs
• TREATMENT OF LONG DISTANCE
• DEPENDENCIES IN LFG
• TAG FUNCTIONAL UNCERTAINTY IN LFG IS A COROLLARY IN TAG
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• Database System
• Cơ sở dữ liệu
• Lecture Database
• Data modeling
• Relational databases
• Relation attributes
• Fundamentals of Database Systems
• Database Systems
• Normalization for relational databases
• Lecture Database systems
• Top Down database design
• Closure of sets of FDs
• Nonprime attributes
• Database management systems
• Lecture Database management systems
• Trivial FDs
• Armstrong’s axioms
• Redundancy of FDs
• Normalization for relational DBs
• Direct dependency
• Data cleansing
• Conditional functional dependencies
• Cause of errors
• Multi tuple violations
• Traditional functional dependencies
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• constituent structure
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• constraining equation
• Long Distance Dependencies
• Minigrammar of English
• Inference Rules for FDs
• Equivalence of Sets of FDs
• Minimal Sets of FDs
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• Database Management System
• Phụ thuộc hàm
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• Lecture Database system
• Relational database
• Key finding algorithms
• Phụ thuộc hàm xấp xỉ
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• Approximate functional dependencies
• Association rules
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