Databases Demystified a self teaching guide phần 4 ppsx

... that ends every SQL statement. In Oracle, a transaction is automatically started for each database user session as soon as the user connects to the database. At any time, the database user can ... table’s data. The ALTER TABLE Statement The ALTER TABLE statement may be used to change many aspects of the definition of a database table. Again, there is a wide variation in implementation a...

Ngày tải lên: 08/08/2014, 18:22

... databases, including properties common to databases, prevalent database models, a brief his - tory of databases, and the rationale for focusing on the relational model. Properties of a Database A ... Logical Database Design Using Normalization 145 The Need for Normalization 147 Insert Anomaly 148 Delete Anomaly 148 Update Anomaly 148 Applying the Normalization Process 148 Choo...

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... screen Constraints A constraint is a rule placed on a database object (typically a table or column) that restricts the allowable data values for that database object in some way. These are most important ... relational databases were built by both IBM and UC Berkeley. e. Nearly all the commercial relational databases are descendents of either System R or INGRES. 18. Currently avai...

Ngày tải lên: 08/08/2014, 18:22

... row are called aggregate functions. The following table shows aggregate functions that are commonly used in relational databases: Function Name Description AVG Calculates the average value for a ... one-to-many, one-to-one, or many-to-many 5. The Microsoft Access Show Table dialog box: a. Lists all tables in the database and allows for the metadata about tables to be added, changed, and...

Ngày tải lên: 08/08/2014, 18:22

... systems. Databases that store historical data used solely for analytical purposes are not as subject to insert, update, and de - lete anomalies. Chapter 12 contains more information on databases that ... normalization rules • Storing redundant data in tables • Storing summarized data in tables Note also that normalization is intended to remove anomalies from databases that are used for...

Ngày tải lên: 08/08/2014, 18:22

... profile Composite Default screen 1 94 Databases Demystified Demystified / Databases Demystified / Oppel/ 2253 64- 9 / Chapter 7 The Data Flow Diagram The data flow diagram (DFD) is the most data centric of all the ... form relation becomes a. An index b. A referential constraint c. A table d. A view e. A database 4. The insert anomaly refers to a situation where: a. Data...

Ngày tải lên: 08/08/2014, 18:22

... several proprietary XML databases on the market. However, businesses have been reluctant to abandon relational data - bases and undergo a major paradigm shift in the way they organize and store data. So, ... considered a best practice because it can lead to a lack of data sharing. Moreover, placing geographic or organizational unit names in table names plays havoc every time the organ...

Ngày tải lên: 08/08/2014, 18:22

... even to a different version of the same vendor’s database). Connecting Databases to Java Applications Java started as a proprietary programming language (originally named Oak) that was developed ... that binds the API to the particular database and platform, and a definition known as the ODBC data source contains the information necessary for a particular application to connect with...

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... profile Composite Default screen CHAPTER 12 Databases for Online Analytical Processing 301 Demystified / Databases Demystified / Oppel/ 2253 64- 9 / Chapter 12 Data Marts A data mart is a subset of a data warehouse ... contains more data than a data warehouse. e. The project has a lower overall cost than a data warehouse project. 16. Building a data warehouse first, foll...

Ngày tải lên: 08/08/2014, 18:22

... Default screen J Java applications, connecting databases to, 241 – 242 Java Database Connectivity, 241 – 242 Java Relational Binding, 242 Java SQL, 242 JDBC, 241 – 242 joining, 14 inner joins, 72– 74, ... 62–63 D Data Control Language (DCL), 90, 122–1 24 Data Definition Language (DDL), 90, 118–122 data encryption, 256–257 data flow diagram, 1 94 196 data integrity, 2 14 Data Manipu...

Ngày tải lên: 08/08/2014, 18:22