Tài liệu, ebook Cơ Sở Dữ Liệu

 Further Reading: [1] Chapter 15 & 16  4NF: based on multivalued dependency (MVD).  5NF: based on join dependency.  Such a dependency is very difficult to detect in practice.  Normalization into 5NF is considered very rarely in practice.  Other normal forms & algorithms.  ER modeling: top-down database design.  Bottom-up database des...

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VIEW (6)  Views defined on multiple tables using joins are generally not updatable.  Views defined using grouping and aggregate functions are not updatable.  The clause WITH CHECK OPTION must be added at the end of the view definition if a view is to be updated.  An in-line view: the view is defined in the FROM clause of an SQL query.

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Tìm kiếm trên BST Chọn hướng tìm theo tính chất của BST: So sánh với node gốc, nếu đúng thì tìm thấy Tìm bên nhánh trái (hay phải) nếu khóa cần tìm nhỏ hơn (hay lớn hơn) khóa của node gốc Giống phương pháp tìm kiếm nhị phân Thời gian tìm kiếm Tốt nhất và trung bình: O(lg n) Tệ nhất: O(n)

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Domain Relational Calculus (1)  The formal specification of the domain calculus was proposed after the development of the QBE language and system.  Domain calculus differs from tuple calculus in the type of variables used in formulas: the variables range over single values from domains of attributes.  To form a relation of degree n for a q...

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 Step 9: Mapping of Union Types (Categories)  Create a new relation S for the category with a primary key.  Include any attributes of the category in S.  If superclasses have different keys:  Include a new key attribute, called surrogate key, as foreign key in each relation of the superclasses.  These foreign keys reference to the prima...

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Physical database design  The process of producing a description of the implementation of the database on secondary storage.  Describes the base relations, file organizations, and indexes design used to achieve efficient access to the data, and any associated integrity constraints and security measures.

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Exercise 3 (2)  Attic keeps track of its clients through the assigning of client numbers. They also keep track of clients’ names and addresses.  When Attic sells an item to a client, they need to keep track of the actual selling price, the date of the sale, and the sales tax.  When Attic buys an item, they wish to track the purchase cost, c...

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Problems with ER Models (2)  Fan Trap  Where a model represents a relationship between entity types, but pathway between certain entity occurrences is ambiguous.  Usually: two or more 1:N relationships fan out from the same entity.  Chasm Trap  Where a model suggests the existence of a relationship between entity types, but pathway do...

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AVL Trees as Arrays? We previously saw that: – Complete tree can be stored using an array using Q(n) memory – An arbitrary tree of n nodes requires O(2n) memory Is it possible to store an AVL tree as an array and not require exponentially more memory?

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Summary In this topic, we covered binary search trees – Described Abstract Sorted Lists – Problems using arrays and linked lists – Definition a binary search tree – Looked at the implementation of: • Empty, size, height, count • Front, back, insert, erase • Previous smaller and next larger objects

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