slide co so du lieu

... định nghĩa: <!ATTLIST sender company CDATA #FIXED "Microsoft"> Trang 39<!ENTITY writer "Donald Duck."><!ENTITY copyright "Copyright W3Schools."> + File ... (#PCDATA)> <!ELEMENT body (#PCDATA)> Trang 33 Khai báo element con xuất hiện một lần duy nhất trong element cha Khai báo element con không xuất hiện hoặc xuất hiện nhiều lần trong element cha. ... #REQUIRED <!ATTLIST contact fax CDATA #IMPLIED> + Nội dung file XML hợp lệ là: <contact fax="555-667788" /> Hoặc: <contact /> Trang 3821/10/14 Cơ sở dữ liệu XML 38DTD

Ngày tải lên: 21/10/2014, 22:50

... Trang 1Nội dung• Giới thiệu • Một số khái niệm • Ràng buộc toàn vẹn • Các đặc trưng của quan hệ • Chuyển đổi mô hình E/R sang mô hình quan hệ Trang 2GIỚI THIỆUTrang 3Giới thiệu• Do E F Codd đưa ... 2GIỚI THIỆUTrang 3Giới thiệu• Do E F Codd đưa ra – “A Relation Model for Large Shared Data Banks”, Communications of ACM, 6/1970 • DBMS đầu tiên ứng dụng mô hình quan hệ – System R, được phát triển ... tập các giá trị đơn gắn liền với một thuộc tính Kiểu dữ liệu cơ sở • Mảng (array) • Bản ghi (record) Trang 12Định nghĩa hình thức• Lược đồ quan hệ – Cho A1, A2, …, An là các thuộc tính – Có các

Ngày tải lên: 07/12/2021, 17:30

... lvminh@fit.hcmus.edu.vn Trang 37Kiến trúc của HQT CSDL43 DDL Compiler User/Application Database Administrator Query Compiler Transaction Manager Execution Engine Logging & Recovery Concurrency Control ... Concurrency Control Index/File/ Record Manager Storage Manager Storage DDL Commands Transaction Commands Data, Metadata, Indexes Storage Buffer Manager DDL Commands Transaction Commands Data, Metadata, ... 371/31/2018 ©2017 Lương Vĩ Minh - lvminh@fit.hcmus.edu.vn Trang 32K IẾN TRÚC CỦA HQTCSDLTrang 33Mức trong (Internal Level)Cấu trúc lưu trữ vật lý Mức quan niệm (Conceptual Level) Toàn bộ cấu trúc CSDL cho

Ngày tải lên: 07/12/2021, 17:30

... tới các yếu tố so sánhkhác nh−:  giá của loại năng l−ợng  hiệu suất của các thiết bị  chi phí đầu t− vào các thiết bị khi chuyển đổi Trang 43Hµm LeontiefC¸c hµm d¹ng Cobb Douglas coi sù thay ... thái cực người ta sử dụng hàm dạng tổng quát CES (Constant Elasticity of Substitution) hay còn có tên là SMAC theo tên những người đã tỡm ra hàm này Solow, Minhas, Arrow và Chenery) Trang 60logarit ... Trang 62ở các trường hợp đặc biệt thì hàm CES trở thành hàmCobb Douglass và Leontief Thật vậy ta có Nếu ρ = 0 hay σ = 1 ta có hàm số dạng Cob-douglas (Y= Ea K*b ) (Y= E K* ) Nếu Nếu γ→-∞ hay σ

Ngày tải lên: 18/05/2014, 20:41

... Chapter 1 Introduction to Databases Transparencies © Pearson Education Limited 1995, 2005 Chapter 1 - Objectives  Some common uses of database systems.  Characteristics ... manages its own data. © Pearson Education Limited 1995, 2005 File-Based Processing © Pearson Education Limited 1995, 2005 Limitations of File-Based Approach  Separation and isolation of data – Each ... (DBMS) © Pearson Education... – a user-accessible catalog © Pearson Education Limited 1995, 2005 Views Allows each user to have his or her own view of the database A view is essentially some subset

Ngày tải lên: 21/10/2014, 23:05

... existing databases; – increased performance; – possible reduction in hardware costs; – reduction in communication costs; – increased consistency. Trang 32Traditional Two-Tier Client-ServerTrang ... ModelTrang 21Conceptual ModelingConceptual schema is the core of a system supporting all user views. Should be complete and accurate representation of an organization’s data requirements. Conceptual ... ObjectivesPurpose of three-level database architecture Contents of external, conceptual, and internal levels. Purpose of external/conceptual and conceptual/internal mappings. Meaning of logical and

Ngày tải lên: 21/10/2014, 23:07

... database administrators that define or constrain some aspect of the enterprise. Trang 20◆ Base Relation – Named relation corresponding to an entity in conceptual schema, w hose tuples are phy ... way is to find all combinations of Trang 9Mathematical Definition of Relation◆ Any subset of Cartesian product is a relation; e.g. Trang 10Mathematical Definition of Relation◆ Consider three sets ... must match a candidate key v alue of some tuple in its home relation or foreign key v alue must be w holly null. Trang 19Integrity Constraints◆ General Constraints – A dditional rules specified

Ngày tải lên: 21/10/2014, 23:07

... in common columns of S are also included in Trang 29Example - Left Outer join Produce a status report on property viewings. ΠpropertyNo, street, city (PropertyForRent) Viewing © Pearson Education ... Cartesian product List the names and comments of all clients who have viewed a property for rent. (ΠclientNo, fName, lName (Client)) X (ΠclientNo, propertyNo, comment (Viewing)) © Pearson Education ... properties for rent. © Pearson Education Limited 1995, 2005 Trang 16– Defines a relation consisting of the set of all tuples that are in both R and S – R and S must be union-compatible. Expressed

Ngày tải lên: 21/10/2014, 23:08

... Pearson Education Limited 1995, 2005 17 SELECT... Limited 1995, 2005 31 Example 5.7 Range Search Condition © Pearson Education Limited 1995, 2005 32 Example 5.7 Range Search Condition x x Also ... include: – ISO’s Information Resource Directory System (IRDS) Standard – Remote Data Access (RDA) Standard © Pearson Education Limited 1995, 2005 13 Writing SQL Commands x SQL statement consists ... names of various database objects such as relations, columns, views – © Pearson Education Limited 1995, 2005 14 Writing SQL Commands x x Most components of an SQL statement are case insensitive,

Ngày tải lên: 21/10/2014, 23:08

... 23ALTER TABLEAdd a new column to a table. Drop a column from a table. Add a new table constraint. Drop a table constraint. Set a default for a column. Drop a default for a column. Trang 24Example ... of columns produced by subselect If omitted, each column takes name of corresponding column in subselect Trang 30SQL - CREATE VIEWList must be specified if there is any ambiguity in a column ... existence on continued existence of view being dropped, command is rejected Trang 38View Resolution(a) View column names in SELECT list are translated into their corresponding column names

Ngày tải lên: 21/10/2014, 23:14

... 2005 6 Introduction to Microsoft Access © Pearson Education Limited 1995, 2005 7 Summary of Microsoft Access Query Types © Pearson Education Limited 1995, 2005 8 Introduction to Microsoft Access ... Select records according to some criteria. - Perform calculations on the data in tables. - Insert and delete records. - Modify values of fields. - Create new fields and tables. © Pearson Education ... has proved so popular that QBE (or similar) is now provided by most DBMSs.  When user constructs a QBE - in background, DBMS creates an equivalent SQL statement. © Pearson Education Limited

Ngày tải lên: 21/10/2014, 23:16

... late 1960s, led to ‘software crisis’, now refer to as the ‘software depression’. © Pearson Education Limited 1995, 2005 6 Software Depression ◆ Major reasons for failure of software projects ... spent on maintenance began to absorb resources at an alarming rate. © Pearson Education Limited 1995, 2005 5 Software Depression ◆ As a result, many major software projects were – late, – ... and tasks associated with data administration and database administration. © Pearson Education Limited 1995, 2005 4 Software Depression ◆ Last few decades have seen proliferation of software

Ngày tải lên: 21/10/2014, 23:16

... produced during the database application lifecycle © Pearson Education Limited 1995, 2005 Trang 8Fact-Finding Techniques ◆ A database developer normally uses several fact-finding techniques during ... commonly used fact-finding techniques ◆ How to use each fact-finding technique and the advantages and disadvantages of each ◆ About a property rental company called DreamHome © Pearson Education ... of using techniques such as interviews and questionnaires to collect facts about systems, requirements, and preferences. © Pearson Education Limited 1995, 2005 Trang 6When Are Fact-Finding Techniques

Ngày tải lên: 21/10/2014, 23:18

... entity type. © Pearson Education Limited 1995, 2005 6 Examples of Entity Types © Pearson Education Limited 1995, 2005 7 ER diagram of Staff and Branch entity types © Pearson Education Limited ... Branch user views of DreamHome © Pearson Education Limited 1995, 2005 4 Concepts of the ER Model ◆ Entity types ◆ Relationship types ◆ Attributes © Pearson Education Limited 1995, 2005 5 Entity ... modeling Transparencies © Pearson Education Limited 1995, 2005 2 Chapter 11 - Objectives ◆ How to use Entity–Relationship (ER) modeling in database design. ◆ Basic concepts associated with ER model.

Ngày tải lên: 21/10/2014, 23:20

... ObjectivesLimitations of basic concepts of the ER model and requirements to represent more complex applications using additional data modeling concepts Most useful additional data modeling concept of Enhanced ... participation constraints – disjoint constraints Participation constraint – Determines whether every member in superclass must participate as a member of a subclass Trang 14Constraints on ... into job roles and contracts of employment Trang 12EER diagram with shared subclass and subclass with its own subclass Trang 13Constraints on Specialization / Generalization Two constraints that

Ngày tải lên: 21/10/2014, 23:20

... Self-determination A → A (5) Decomposition If A → B,C, then A → B and A → C © Pearson Education Limited 1995, 2005 [...]... least one attribute in common © Pearson Education Limited 1995, 2005 16 ... BCNF) © Pearson Education Limited 1995, 2005 17 Review of Normalization (UNF to BCNF) © Pearson Education Limited 1995, 2005 18 Review of Normalization (UNF to BCNF) © Pearson Education Limited ... Boyce–Codd Normal Form (BCNF).  How to represent attributes shown on a report as BCNF relations using normalization. © Pearson Education Limited 1995, 2005 4 Chapter 14 - Objectives  Concept

Ngày tải lên: 21/10/2014, 23:20

... methodology. © Pearson Education Limited 1995, 2005 [...]... Database Design Methodology x Step 1 Build conceptual data model (continue) – Step 1.6 Consider use of enhanced modeling concepts (optional ... document the details of each... redundant relationship called Rents © Pearson Education Limited 1995, 2005 29 Example of a non-redundant relationship FatherOf © Pearson Education Limited 1995, 2005 ... design. © Pearson Education Limited 1995, 2005 6 Database Design Methodology ◆ Three main phases – Conceptual database design – Logical database design – Physical database design © Pearson Education

Ngày tải lên: 21/10/2014, 23:20

... the relationship by combining the entities involved into one relation or by creating two relations and posting a copy of the primary key from one relation to the other – Consider the following ... of the new relation, possibly in combination with some of the attributes of the relationship Trang 17Step 2.1 Derive relations for logical data model  (8) Complex relationship types – Create ... ‘many’ relationship (for example, 1 *, 0 *) generally will also form the primary key of this new relation, possibly in combination with some of the attributes of the relationship Trang 18Step 2.1

Ngày tải lên: 21/10/2014, 23:21

... database design is concerned with the what, physical database design is concerned with the how. © Pearson Education Limited 1995, 2005 5 Physical Database Design Process of producing a description ... Pearson Education Limited 1995, 2005 8 Overview of Physical Database Design Methodology ◆ Step 5 Design user views ◆ Step 6 Design security mechanisms ◆ Step 7 Consider the introduction of controlled ... constraints on the domain; – an optional default value for the attribute; – whether it can hold nulls; – whether it is derived, and if so, how it should be computed © Pearson Education

Ngày tải lên: 22/10/2014, 10:09

... efficiency.How system resources affect performance. Trang 3Step 7 Consider the Introduction of Controlled Redundancy To determine whether introducing redundancy in a controlled manner by relaxing ... Consider the Introduction of May be necessary to accept loss of some benefits of a fully normalized design in favor of performance Trang 5Step 7 Consider the Introduction of Controlled Redundancy ... Trang 7Step 7 Consider the Introduction of Controlled Redundancy Consider denormalization in following situations, specifically to speed up frequent or critical transactions: – Step 7.1 Combining

Ngày tải lên: 22/10/2014, 10:10