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In today's competitive environment, an organization needs a comprehensive, secure, reliable, and productive data platform for its business applications. The SQL Server 2005 database engine provides a platform that allows building and managing data applications. In addition, SQL Server 2005 combines data analysis, reporting, integration, and notification services to enable organizations to build and deploy efficient Business Intelligence (BI) solutions. This chapter discusses the importance of a database server. In addition, it provides an overview of SQL Server 2005, its components, and features. The chapter introduces the Structured Query Language (SQL) that is used to manipulate data in a database server. Lastly, it discusses the tools provided by SQL Server 2005 to improve the productivity of the database developer and manage the server. Objectives In this chapter, you will learn to:  Appreciate SQL Server 2005 as a database server  Identify the SQL Server 2005 tools Chapter 1 Overview of SQL Server 2005 Introduction to SQL Server 2005 Every organization needs to maintain information related to employees, customers, business partners, or business transactions. Organizations build business applications with a user-friendly interface to store and manipulate this information and to generate reports. In addition, they need a platform that can be used to store and maintain this information in an efficient way. Various database management system (DBMS) and relational database management system (RDBMS), such as SQL Server 2005, Oracle, and Sybase, can be used to maintain this information. SQL Server 2005 is a data engine introduced by Microsoft. It lies at the core of the data management solution of an organization. It allows secure and efficient storage and management of data. In addition, SQL Server 2005 provides other components and services that support the business intelligence platform to generate reports and facilitate data analysis. As a database developer, it is important for you to identify the role of a database server in an organization. To effectively design and implement database solutions by using SQL Server 2005, it is important for you to identify its components and services. In addition, you need to understand the basics of SQL, a language that is used to query and manage data. Role of a Database Server Organizations have always been storing and managing business data. Earlier, organizations used to store the data on paper. With an increase in the usage of computers, organizations began building and using business applications to support the business operations. The business applications accept data as input, process the data based on business requirements, and provide data or information as output. For example, an application that maintains the sales details for an organization, accepts the details of the sales transaction from the users. The data is saved and an output message confirming that the data has been saved is displayed to the user. For example, the Human Resource department of an organization uses an application to manage the employee data. The users need to add the details of new employees. For this, the application provides an interface to enter the employee details. These details are validated for accuracy based on business rules. For example, a business rule is defined to check that the date of joining of the new employee is less than or equal to the current date. If the data meets the requirements, it is saved in the data store. ¤NIIT Overview of SQL Server 2005 1.3 Based on the preceding scenario, a business application can have three elements: „ The user interface or the presentation element, through which data is input. „ The application logic or the business rule element, which helps in implementing the operations to be performed on the input data. „ The data storage or the data management element, which manages the storage and retrieval of data. These elements form the base of the models or architectures used in application development. Depending on the placement of these elements, the application architectures can be categorized as: „ Single-tier architecture „ Two-tier architecture „ Three-tier architecture „ N-tier architecture Single-Tier Architecture In single-tier architecture, all elements of a business application are combined as a single executable unit. This executable unit is installed on all the computers that the users need to work on. In this case, it becomes complicated to modify the application or to fix any bugs. This is because, after modifying the application, it is required to recompile and redistribute the entire application to all the computers. Two-Tier Architecture To address the problems in modifying an application faced in a single-tier application, two-tier architecture was evolved. In two-tier architecture, the application is divided into two manageable parts; one part handles the data, while the other provides the user interface. Therefore, this architecture is called two-tier architecture. The two parts can be located on a single computer or on separate computers over a network. 1.4 Overview of SQL Server 2005 ¤NIIT The part that handles the user interface (UI) is called the client tier. The part that implements the application logic and manages the input data based on the business rules is called the server tier, as shown in the following figure. A Two-Tier Architecture In this architecture, the maintenance, upgrade, and general administration of data is easier, as it exists only on the server and not on all the clients. Two-tier architecture is also called client-server architecture. Most RDBMSs, such as Microsoft Access, SQL Server, and Oracle, adhere to the client-server architecture. RDBMS provides centralized functionality required while supporting many users. Three-Tier Architecture When implementing complex business solutions in case of a two-tier architecture, the tier on which the business logic is implemented becomes over loaded. As a result, it takes more time to execute. Therefore, to provide further flexibility, the two-tier architecture can be split into three tiers. In three-tier architecture, the first tier is the client tier, the second or middle tier is called the business tier, and the third tier is called the server tier. The server tier contains a database server that manages the data. ¤NIIT Overview of SQL Server 2005 1.5 In this architecture, an additional tier called a business tier has been added between the client tier and the server tier of the two-tier architecture, as shown in the following figure. A Three-Tier Client/Server Architecture The business tier consists of all the business rules. It consists of the application logic that implements rules and checks the data. The advantage of a three-tier application is that it allows you to change the business rules without affecting the other two tiers. For instance, in a banking application for loans, the user tier is the front-end used by the customer to specify the loan details. The server tier can consist of an RDBMS in which the data is stored. The business tier lies between the other two tiers and consists of business rules, such as the loan limit and the interest rate charged to a customer. If there is a change in the rate of interest, only the middle tier component needs to be modified. N-Tier Architecture As the business complexities increased, the business tier became larger and unmanageable. This led to the evolution of n-tier architecture, where the business services model was divided into smaller manageable units. N-tier architecture is also called as multi-tier architecture. In this architecture, it is possible to keep the UI-centric processing on a computer near the client. In addition, you may keep the data-centric processing components on another computer near the database server, so that you gain significant performance benefits. 1.6 Overview of SQL Server 2005 ¤NIIT The N-tier architecture consists of the following layers: „ Client tier „ UI-centric processing components „ Data-centric processing objects „ Database server The banking application, when further expanded, can depict an example of n-tier architecture. The client tier would deal with the user interface, which would include the user interface controls, such as forms, menus, and toolbars. The server tier would comprise data-handling including saving data to the database server. The business logic would include the rules and guidelines for different types of accounts, interest rates, fixed deposits, ATMs, and overdrafts. All these would form the middle tier. However, there would be some rules that need to be implemented on the user interface and on the database. You can place these rules either on the UI-centric processing components or data-centric processing components, based on the functionality. Applications that follow multi-tier architecture can be used across various locations. For example, in Web applications, the application is stored on the Web server. The clients access the application from any location through a browser software. The clients make requests and receive responses from the Web server. ¤NIIT Overview of SQL Server 2005 1.7 The Web server transfers the request for data to a database server, as shown in the following figure. Architecture of Web Applications Depending on the relevance of the business rules, they can be implemented on any of the tiers, such as the Web clients, Web server, or the database server. To provide support to applications where users can send requests simultaneously, the database server needs to be a fast, reliable, and secure. SQL Server 2005 is one such comprehensive database platform that provides a fast, reliable, and secure RDBMS. It also helps in data analysis with integrated BI tools. Note A BI application is an application that is used by the top management of an organization for data analysis to make future decisions. BI tools are the tools that help in creating reports that enable data analysis. 1.8 Overview of SQL Server 2005 ¤NIIT SQL Server 2005 Components SQL Server 2005 contains a number of components. Each component provides specific services and support to the clients connected to the server. The following figure depicts the components of SQL Server 2005. Components of SQL Server 2005 As shown in the preceding figure, SQL Server 2005 consists of the following core components: „ Database Engine „ Integration Services „ Analysis Services „ Reporting Services Database Engine The database engine provides support to store, query, process, and secure data on the database server. The database engine contains databases and database objects, such as tables and procedures. This database engine allows you to create and manage database objects. Apart from providing support for data management, the database engine also provides the following background services: „ Service Broker: Provides support for asynchronous communication between clients and the database server, enabling reliable query processing. The client application sends a request to the database server and continues to work. The requests sent by the client are queued up at the server, in case the server is not available to process the request immediately. Server Broker ensures that the request is processed whenever the server is available. ¤NIIT Overview of SQL Server 2005 1.9 „ „ „ Replication: Allows you to copy and distribute data and database objects from one database server to another. These servers can be located at remote locations to provide fast access to users at widely distributed locations. After replicating data, the SQL Server allows you to synchronize different databases to maintain data consistency. For example, the database servers for your organization might be located at different locations around the world. All the servers store common data. To ensure that the data in all the servers is synchronous, you can implement data replication. Full-text search: Allows you to implement fast and intelligent search in large databases by allowing you to search records containing certain words and phrases. You can search for different forms of a specific word, such as ‘produce’, ‘produces’, or ‘production’. In addition, you can search for synonyms of a given word, such as ‘garment’, ‘cloth’, or ‘fabric’. Notification services: Allows you to generate and send notification messages to the users or administrators about any event. For example, the database administrator should be notified when a database object, such as a table is created or deleted. The notification messages can be sent to a variety of devices, such as computers or mobile devices. Integration Services Integration services allow you to gather and integrate data from various disparate data sources available in an organization. You can store the data in a consistent format in a common database called the data warehouse. For example, data in your organization might be stored in different databases, such as Microsoft Access, FoxPro, or text files. You might need to consolidate data from all these sources and save the data in a common set of tables on a database server. Integrating data from different sources that might be stored in different formats and structures involves various complex operations to resolve data quality issues and convert the data into a common format. The integration services provide a set of tasks that help the developer create data integration projects with minimum lines of code. Data integration allows collation of data from all the data sources in a common format to enable accurate analysis of data. Analysis Services Analysis services help in data analysis in a BI application. These applications are built on a data warehouse that contains data consolidated from various data sources. These services provide data mining solutions that are built on data integrated in the data warehouse. Data mining solutions allow the users to query and present data in reports that enable business forecasts, such as expected sales or profit estimates in the next financial year. 1.10 Overview of SQL Server 2005 ¤NIIT