Primary keys

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  • Issues Involved When Updating the Primary Key of a Parent Row In this section, you'll learn about the issues involved when attempting to update the primary key in a parent DataTable

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  • [ Team LiB ] Recipe 4.6 Adding Records with a GUID Primary Key Problem You want to add records to a DataTable that uses a GUID as its primary key and has related child records. Solution Use the DataTable.RowChanging event handler.

    pdf4p luvpro 04-08-2010 60 5   Download

  • [ Team LiB ] Recipe 4.8 Updating a Primary Key Value Problem You changed a primary key value in a DataTable and updated the change back to the underlying data source, but the value in the data source remained unchanged.

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  • [ Team LiB ] Recipe 4.5 Adding Parent/Child Rows with Auto-Incrementing Keys Problem You want to insert related parent/child rows into a DataSet where the primary key of the parent table is an automatically incrementing value.

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  • 2,3 Xác định một khóa và các chỉ số chỉ số chính được sử dụng để cải thiện hiệu suất khi truy vấn dữ liệu, chẳng hạn như tìm kiếm trên các lĩnh vực và phân loại thông tin.

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  • 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.

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  • GUIDELINE 3: Relations should be designed such that their tuples will have as few NULL values as possible  Attributes that are NULL frequently could be placed in separate relations (with the primary key)  Reasons for nulls: attribute not applicable or invalid attribute value unknown (may exist) value known to exist, but unavailable

    ppt60p thienthanoze 12-11-2012 25 2   Download

  • Database System: Chapter 8 - Normalization for Relational Databases includes Normal Forms Based on Primary Keys (Normalization of Relations, Practical Use of Normal Forms, Definitions of Keys and Attributes Participating in Keys,...), General Normal Form Definitions (For Multiple Keys), BCNF (Boyce-Codd Normal Form).

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  • Bacterial biofilms are regarded to be the primary aetiological factor in the initiation of gingival inflammation and subsequent destruction of periodontal tissues (Offenbacher 1996) and three major specific pathogens have been repeatedly identified as etiologic agents, namely Aggregatibacter (Actinobacillus) actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg) and Tannerella forsythia (Tf) (Socransky et al. 1998).

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  • This document serves as a design guide for those intending to deploy a site-to-site VPN based on IP Security (IPsec). The designs presented in this document focus on Cisco IOS VPN router platforms. The primary topology described in this document is a hub-and-spoke design, where the primary enterprise resources are located in a large central site, with a number of smaller sites or branch offices connected directly to the central site over a VPN. A high-level diagram of this topology is shown in Figure 1....

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  • 1/ Hệ Quản Trị CSDL? 2/ Cơ Sở Dữ Liệu là gì? 3/ Table là gì? 4/ Khóa chính/Primary key? 5/ Khóa ngoại/Foreign key? 6/ Quan hệ/ relationship? 7/ Ràng buộc, tham chiếu dữ liệu/references? 8/ Duy nhất dữ liệu / Unique? 9/ Truy vấn/ query? II. SQL - Structure Query Language 1/ Ngôn ngữ định nghĩa dữ liệu 2/ Ngôn ngữ thao tác dữ liệu.

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  • As industries turn increasingly hostile, it is clear that strong brand-building skills are needed to survive and prosper. In David Aaker's pathbreaking book, Managing Brand Equity, managers discovered the value of a brand as a strategic asset and a company's primary source of competitive advantage. Now, in this compelling new work, Aaker uses real brand-building cases from Saturn, General Electric, Kodak, Healthy Choice, McDonald's, and others to demonstrate how strong brands have been created and managed....

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  • Family and Friends is a complete six-level course of English for children in primary schools. It uses a clear grammarbased curriculum alongside parallel syllabi in skills and phonics. In this way, children develop the confidence and competence to communicate effectively in English, as well as understanding and processing information from a wide range of sources.

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  • Building Vocabulary Skills & Strategies series. Heres a great vocabulary program that is equally appropriate for younger students working at grade level and older students who have forgotten or never mastered the basics. The friendly look and tone of this series belies the comprehensive sweep of the instructional sequence. Every topicfrom primary level phonics to the specialized terminology of essay testsis developed from the ground up. Includes answer key

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  • Các bước thực hiện với CSDL: 1. Tạo 1 CSDL ( thông thường chỉ cần làm 1 lần ) 2. Mở CSDL đó 3. Thêm giá trị vào trong table 4. Truy vấn. 5. Đóng CSDL 1. Tạo cơ sở dữ liệu. Đầu tiên các bạn add 1 class DBAdapter để xử lý tất cả các thao tác liên quan đến CSDL.

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  • Nếu bạn cố thử chạy phát biểu INSERT này, bạn sẽ nhận một thông báo lỗi từ co8 sở dữ liệu : Violation of PRIMARY KEY constraint 'PK_Customers'. Cannot insert duplicate key in object 'Customers'. The statement has been terminated. Hãy xem nhũng gì sẽ sảy ra khi bạn cố sửa đổi một khoá chính ở bảng cha có một giá trị đã được tham chiếu từ một khoá phụ trong bảng con.

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  • Hãy đặt khóa chính (Primary Key) và tạo quan hệ (Relationships) cho các table như sau...

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  • Bài Viết Trên Đã nói qua.

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  • SQL query: CREATE TABLE IF NOT EXISTS `jos_book_category` ( `id` int(11) NOT NULL AUTO_INCREMENT, `category` varchar(200) NOT NULL, `created_by` int(11) NOT NULL, `created` datetime NOT NULL DEFAULT '0000-00-00 00:00:00', `modified_by` int(11) NOT NULL, `modified` datetime NOT NULL DEFAULT '0000-00-00 00:00:00', `ordering` int(11) NOT NULL, `hits` int(11) NOT NULL, `published` tinyint(1) NOT NULL DEFAULT '0', PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;

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  • - Phân biệt các khái niệm: Super Key, Key, Candidate Key, Primary Key, Foreign Key *** Chương 3. Giáo trình CSDL, Đồng Thị Bích Thủy – Nguyễn Trần Minh Thư – Phạm Thị Bạch Huệ *** Chương 2 (trang 25~35). Giáo trình Nhập môn CSDL - Nguyễn An Tế - Thao tác cơ bản trên các Quan hệ (thao tác cập nhật) *** Chương 3. Giáo trình CSDL, Nguyễn Đăng Tỵ - Đỗ Phúc

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