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Overview
Product Details
| ISBN-13: | 9781576102695 |
|---|---|
| Publisher: | Coriolis Group |
| Publication date: | 03/23/2000 |
| Series: | Exam Prep Series |
| Edition description: | BK&CD ROM |
| Product dimensions: | 7.63(w) x 9.46(h) x 1.87(d) |
Read an Excerpt
Chapter 1: Introduction To Microsoft SQL Server
A Brief Introduction To SQLIn the mid 1970s, IBM created a simple language for accessing and manipulating data stored in database systems. The language was known as the Structured English Query Language, or simply SEQUEL. The benefits of a language that allowed access to data through simple English-language statements were tremendous. Eventually, the popularity of the idea led to IBM's efforts becoming standardized into what we now know as the Structured Query Language, or SQL. Because of its heritage, it is common and acceptable to pronounce SQL as either "see-kwel" or "S-Q-L."
The standardizing body for SQL is primarily the American National Standards Institute (ANSI), although SQL has been embodied within standards issued by other organizations. The current standard is referred to as ANSI-92. It defines a core set of language elements that are common to all implementations of ANSI-compliant SQL systems.
Note: Since the emergence of ANSI-92, a new standard that incorporates many object-oriented features into SQL has been in the works. Originally dubbed SQL3, it is now being ratified and will inherit the common name ANSoblem is especially common with the 3Com Impact adapter running firmware version 2.02. If you think the second telephone number might be the problem, try reconfiguring your adapter to use only one of your ISDN numbers.
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There are now systems from many vendors that implement some form of a SQL product. Microsoft,Oracle, IBM, and Sybase are among the leaders in this segment of the software industry. Each vendor offers a package that leverages the SQL language, though each implementation is very different. The focus of this book will be on Microsoft's product, SQL Server. Before delving into SQL Server, though, it is important to understand the framework within which SQL Server functions.
Database Frameworks
There are several commonly used frameworks for providing access to data on a network. The client/server model has become one of the more popular models, but the simpler file server model and the legendary host model still hold considerable merit.
The File Server Framework
In a typical file server model, a client application accesses data located on the file server. The file server is not providing any intelligence other than a mechanism for data storage and data retrieval. All management of the data is handled by an application running on a client computer. The client always accesses the data directly on the file server.
This framework is most often seen in legacy database systems. A good example might be an employee directory stored in a spreadsheet on a networked file server. The file server is merely acting as a storage location for the spreadsheet. All intelligence for manipulating the directory resides in the spreadsheet application, which runs on the workstation computers. When employee information needs to change, someone loads the spreadsheet, changes the data, and then saves the spreadsheet back to the file server. Microsoft Access is an example of a current database offering that uses this framework.
File server systems present some challenges to a network administrator, though. Because there is no intelligence on the file server, multiuser access to the file is not always possible. Typically, only one user at a time would be able to modify data. Security is another concern. Any user needing to modify data within the data file would be given the ability to modify all data within the data file. On the other hand, the file server framework is often one of the least expensive to implement.
The Host System Framework
The host system framework is one that relies on the intelligence of a central computer for all operations. Client computers typically are display terminals only (sometimes called a "dumb terminal"). A mainframe environment is a typical host system framework.
In this model, the database application actually executes on the central computer. The central computer is not only responsible for managing the database; it's also responsible for hosting all client sessions and maintaining sessions for all connecting clients.
The Client/Server Framework
SQL Server is a client/server database system. The term "client/server" is a general term used to describe the method in which users access and utilize resources on a network. The client is a process that runs on a user computer and requests some sort of service from a network resource. The server is a process that runs on a remote computer and responds to the requests from the client. Client/server systems are in use in many different technologies. Email is commonly implemented in a client/server model. In a typical email scenario, a user opens an application such as Microsoft Outlook, and the user's email is downloaded to the application. In this case, the email application, Outlook, is acting as the client process. It connects to a server process, an email server such as Microsoft Exchange, and requests all documents belonging to the user.
An important item to note in the client/server architecture is that the client is always communicating with the server. It does not access data on the server directly. In other words, the email client does not directly access messages located on a remote hard disk. Rather, the email client asks the email server for the messages. The email server then retrieves the messages and sends them to the client.
In the case of a database system, SQL Server is fulfilling the server side of the model. SQL Server is managing the database structures and responding to client requests, or queries. Again, the client is not directly accessing or manipulating the database. Instead, the client sends a query to SQL Server, and the server retrieves the data and sends it back to the client. This allows for intelligent processing on the server (in addition to the client), which in turn makes possible many features such as user-level security.
Basic RDBMS Concepts
SQL Server is a relational database management system (RDBMS). A relational database consists of related entities. An entity is some sort of object for which data is collected. For example, a human resources database will likely contain information about employees. The employee thus becomes an entity. The type of data collected will probably include the employee name, address, and telephone number. These are the attributes of the employee. Another example of an entity that might be found in a human resources database is an insurance plan. Insurance plans could have various attributes, such as the name and the cost of the plan.
Each employee is probably assigned to an insurance plan. The insurance plan to which an employee is assigned is another attribute of the employee. Thus, there is a relationship between the employee entity and the insurance plan entity. The idea of relationships between entities is at the heart of a relational database system and is what makes an RDBMS different from nonrelational systems. In an RDBMS, the database system itself maintains the relationships. The end users don't need to have an intimate knowledge of the underlying database structures.
In relational database management systems, entities are implemented as flat, two-dimensional tables, much like a spreadsheet. Each occurrence of an entity is represented by a row in the table. Columns within the table represent attributes. Figure 1.1 depicts two tables with sample data to help show how entities, attributes, and relationships work together.
A user who requests the cost of insurance for a particular employee won't need to know that this information is actually stored in two different tables. Instead, it is the responsibility of the RDBMS to manage relationships between the tables and seamlessly retrieve the requested data. For instance, to find out the cost of insurance for Joseph Sheets, the RDBMS would look in the employee table for the entry belonging to Joseph Sheets. It would then look at the insurance column and see that it contains a reference, or link, to another table, the insurance plan table. More specifically, it refers to the insurance plan with a plan ID of 1. The RDBMS then looks in the insurance plan table for the matching plan ID and sees that the associated cost is $456.
There are several key functionalities provided by an RDBMoblem is especially common with the 3Com Impact adapter running firmware version 2.02. If you think the second telephone number might be the problem, try reconfiguring your adapter to use only one of your ISDN numbers.
Drivers are not supported in Windows 98.
ISDN drivers from the ISDN version 1.0 Accelerator Pack are not supported in Windows 98. Contact your ISDN adapterc;
- Definition of entities into data structures called tables
- Storage, retrieval, and update of data
- Maintenance of entity relationships
- Data integrity through transaction support
- Concurrent access to data
- Recovery of the database from damage
- User identification and security
Microsoft SQL Server has a long and complex history. It hasn't always been called Microsoft SQL Server, it hasn't always run on Windows, and it hasn't even always been developed by Microsoft. In the mid-1980s, Microsoft teamed up with IBM to develop OS/2, and each was marketing a version. IBM was beginning to leverage some of the advanced capabilities of OS/2 to bring to market a more robust version that included a relational database management system. This was unusual at the time because most database systems for PCs were not sophisticated relational systems. The most popular database system for PCs then was Ashton-Tate's dBase, a comparatively simple, flat-file database system.
In an effort to compete with IBM's version of OS/2, Microsoft sought to build a relationship with a database vendor. Sybase, a relative newcomer to the field, had been working on a client/server product with some interesting new features. However, its primary focus was on Unix-based offerings. A marriage between Sybase and Microsoft promised benefits for both companies. Sybase would gain entry into the PC market, and Microsoft would gain access to full-fledged client/server database technology. However, because Ashton-Tate had such a strong hold on the PC database market, they too were brought into the foray to provide credibility. Ashton-Tate would jointly market and sell this new product, to be dubbed the Ashton-Tate/Microsoft SQL Server.
Version 1 was shipped in 1989 and was heralded as a breakthrough for PCs. No longer was a $100,000 piece of hardware required to run a full relational database. Now, for a mere $10,000 personal computer, a company could take care of its database needs and still experience performance that is comparable to, and sometimes better than, the performance of its mid-range and minicomputers. As Ashton-Tate lost market share and began a downward spiral with its other products, Microsoft terminated the relationship. In 1990, Microsoft shipped Microsoft SQL Server 1.1, the first version bearing only the Microsoft name. The database engine at this time was still developed entirely by Sybase, though Microsoft was doing library and client development.
Microsoft and Sybase continued to work together, with Sybase doing the database engine work. Eventually, Microsoft gained access to the engine's code and began doing a lot of joint engine development with Sybase. Upon completion of Microsoft SQL Server 4.2, a 16-bit port of the Sybase Unix engine, Microsoft ended development for the OS/2 platform and shifted entirely to development for the new Windows NT platform. Thus, Microsoft began porting version 4.2 to Windows NT and claimed to have mostly rewritten the kernel of SQL Server in the process.
As Microsoft began doing more of the development, and as the product grew in acceptance, Sybase began losing sales of Unix database systems to NT database systems. This eventually led to an end of the joint development relationship between the two vendors in mid-1994. Agreeing to part ways, Sybase began releasing its own unique product on the NT platform and Microsoft continued forth with Microsoft SQL Server.
Microsoft had been doing most of the development since porting SQL Server to NT. Therefore, it was not much of a surprise that the new version 6 would provide powerful new features that were purely Microsoft. By this time, mid-1995, SQL Server was gaining even more acceptance and becoming quite successful. By early 1996, SQL Server 6.5 was released and proved a phenomenal success.
The current version, SQL Server 7, is turning out to be an even more phenomenal release. Arguably the most significant release of Microsoft SQL Server, this version makes major breakthroughs in all areas, perhaps most notably in administration, performance, and scalability...
Table of Contents
Chapter 1: Introduction To Microsoft SQL Server ..... 1
Chapter 2: Installing SQL Server 7 ..... 19
Chapter 3: Exploring SQL Server 7 ..... 57
Chapter 4: An Overview Of SQL Server Architecture ..... 89
Chapter 5: Security Planning ..... 133
Chapter 6: The Permissions System ..... 169
Chapter 7: Client Connectivity ..... 193
Chapter 8: Managing Databases ..... 217
Chapter 9: SQL Server Backup ..... 253
Chapter 10: Disaster Recovery ..... 299
Chapter 11: Database Dependability ..... 333
Chapter 12: SQL Server Automation ..... 353
Chapter 13: Data Migration ..... 411
Chapter 14: Replication Methodology And Design ..... 457
Chapter 15: Implementing Replication ..... 489
Chapter 16: SQL Server Performance Monitoring ..... 547
Chapter 17: Sample Test ..... 591
Chapter 18: Answer Key ..... 609
Appendix A: Solutions To Review Questions And Case Projects ..... 625
Appendix B: Objectives For Exam 70-028 ..... 673
Appendix C: SQL Primer ..... 677
Glossary ..... 705
Index ..... 717