• Bài giảng Systems Analysis and Design in a Changing World - Chapter 5: Modeling Systems Requirements: Events and ThingsBài giảng Systems Analysis and Design in a Changing World - Chapter 5: Modeling Systems Requirements: Events and Things

    Summary (continued)  Things are what user deals with and system remembers, such as customer placing an order  Traditional approach uses entity-relationship diagrams (ERD) for data entities, attributes of data entities, and relationships between entities  Things are shown as data entities  Object-oriented approach uses class diagrams for...

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  • Chapter 9 Assertions, Views and Programming TechniquesChapter 9 Assertions, Views and Programming Techniques

    Control structure Example: SELECT ProductID, Quantity, UnitPrice, [discount%]= CASE WHEN Quantity <=5 THEN 0.05 WHEN Quantity BETWEEN 6 and 10 THEN 0.07 WHEN Quantity BETWEEN 11 and 20 THEN 0.09 ELSE 0.1 END FROM [Order Details] ORDER BY Quantity, ProductId

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  • Chapter 8 SQL: Schema Definition, Basic Constraints, and QueriesChapter 8 SQL: Schema Definition, Basic Constraints, and Queries

    Insert, delete, and update The UPDATE Command: to modify attribute values of one or more selected tuples.  a WHERE clause in the UPDATE command selects the tuples to be modified from a single relation.  However, updating a primary key value may propagate to the foreign key values of tuples in other relations if such a referential triggere...

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  • Chapter 7 Relational Database Design by ERand EER-To-Relational MappingChapter 7 Relational Database Design by ERand EER-To-Relational Mapping

    Mapping EER Model Constructs to Relations Step 9: Mapping of Union Types (Categories).  For mapping a category whose defining superclass have different keys, it is customary to specify a new key attribute, called a surrogate key, when creating a relation to correspond to the category.  In the example below we can create a relation OWNER t...

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  • Chapter 6 The Relational Algebra and Relational CalculusChapter 6 The Relational Algebra and Relational Calculus

    Tuple Relational Calculus The tuple relational calculus is based on specifying a number of tuple variables. Each tuple variable usually ranges over a particular database relation, meaning that the variable may take as its value any individual tuple from that relation. A simple tuple relational calculus query is of the form {t | COND(t)} w...

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  • Chapter 5 The Relational Data Model and Relational Database ConstraintsChapter 5 The Relational Data Model and Relational Database Constraints

    In-Class Exercise Consider the following relations for a database that keeps track of student enrollment in courses and the books adopted for each course: STUDENT(SSN, Name, Major, Bdate) COURSE(Course#, Cname, Dept) ENROLL(SSN, Course#, Quarter, Grade) BOOK_ADOPTION(Course#, Quarter, Book_ISBN) TEXT(Book_ISBN, Book_Title, Publisher, ...

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  • Chapter 4 Enhanced Entity-Relationship and UML ModelingChapter 4 Enhanced Entity-Relationship and UML Modeling

    Cardinality Constraints Cardinality Constraint: Quantification of the relationship between two concepts or classes (a constraint on aggregation) MINIMUM (A,B) = n: At a minimum, one instance of A is related to at least n instances of B. n = 0 MIN(A,B) = 0 MIN(Person, Car) = 0 n = 1 MIN(A,B) = 1 MIN(Cust, Ship-address) = 1 n = inf. MIN(A,B...

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  • Chương 4. Tìm kiếm (tiếp)Chương 4. Tìm kiếm (tiếp)

    Cây 2‐3  Thực hiện thêm lần lượt các nút sau vào cây 2‐3 ban đầu rỗng: 34, 65, 45, 23, 25, 76, 12, 9, 6, 48, 65, 5, 80, 7  Với cây tạo được ở trên hãy xóa lần lượt các nút: 7, 9, 80, 23

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  • Chương 4 Tìm kiếm (phần 1)Chương 4 Tìm kiếm (phần 1)

    Loại bỏ nút khỏi cây  Nhận xét:  Thực hiện tìm kiếm để xem khóa cần xóa có trên cây  Nếu nút có khóa cần xóa là nút lá: ngắt bỏ kết nối với nút cha của nó, giải phóng bộ nhớ cấp phát cho nút đó  Nếu nút cần xóa là nút trong không đầy đủ (khuyết con trái hoặc phải): Thay thế bằng cây con không khuyết  Nếu nút cần xóa là nút trong đầy đủ ...

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  • Bài giảng Systems Analysis and Design in a Changing World - Chapter 4: Beginning the Analysis: Investigating System RequirementsBài giảng Systems Analysis and Design in a Changing World - Chapter 4: Beginning the Analysis: Investigating System Requirements

    Summary (continued)  Primary information gathering techniques  Review existing reports, forms, and procedure descriptions  Conduct interviews and discussions with users  Observe and document business processes  Build prototype working models  Distribute and collect questionnaires  Conduct JAD sessions  Research vendor solutions

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