Hướng dẫn học Microsoft SQL Server 2008 part 14 pdf

Nielsen c04.tex V4 - 07/23/2009 1:58pm Page 92 www.getcoolebook.com Nielsen c05.tex V4 - 07/21/2009 12:19pm Page 93 Client Connectivity IN THIS CHAPTER Enabling server connectivity SQL Native Client development features Client software connectivity S QL Server 2008 follows Microsoft’s philosophy of ‘‘secure by default’’ and reduces the surface area of the application. The initial installation allows local access only — no network connections for the Express and Developer editions (i.e., remote client applications will not be able to connect). Chapter 4, ‘‘Installing SQL Server 2008’’ discusses SQL Server surface area configuration as part of the installation process. The Server Configuration Manager tool installed with SQL Server can nearly always communicate with SQL Server so you can configure the server connectivity options and open the server up for network access. The connectivity relies on open paths between the client and server machines. At times, there will be firewall issues to deal with. With network access allowed on the SQL Server, SQL Server provides clients with a new means of accessing functionality and features through the new SQL Server Native Client (SNAC). Before getting into the SNAC, network access for the new server must be enabled. Enabling Server Connectivity When initially installed, SQL Server enables the Shared Memory protocol and dis- ables the remaining protocols. This provides the greatest default security because only applications running locally to the SQL Server can connect. To broaden SQL Server availability, additional network protocols must be enabled on the server. 93 www.getcoolebook.com Nielsen c05.tex V4 - 07/21/2009 12:19pm Page 94 Part I Laying the Foundation What’s New in 2008 Connectivity S NAC supports table value parameters. Table-valued parameters are a new parameter type in SQL Server 2008. There is a new SNAC OLE DB provider. You’ll need to get version 10 of SNAC. Also of note for developers, Microsoft Data Access Components (MDAC) is compatible with SQL 2008 but will not be enhanced to support the new 2008 SQL Server features. Chapter 39, ‘‘Configuring SQL Server,’’ discusses SQL Server configuration in detail. Server Configuration Manager When managing SQL Server services, configuring network protocols used by SQL server, or managing the network connectivity configuration from client computers, SQL Server Configuration Manager is the tool you need. Network protocols define the common set of rules and formats that computers and applica- tions use when communicating with one another. Table 5-1 lists the protocols available in SQL Server. TABLE 5-1 SQL Server Protocols Protocol Description Shared Memory This is an in-memory protocol and thus is only suitable for applications that are running on the same machine as the SQL Server. Named Pipes This is an interprocess communications protocol (IPC) that enables a process to communicate with another process, possibly running on a different computer, through the use of shared memory. This protocol typically works well in small and fast local area networks, as it generates additional network traffic during use. In larger and slower networks, TCP/IP works better. TCP/IP TCP/IP, or Transmission Control Protocol/Internet Protocol, is widely used today. TCP guarantees the delivery and order of the information sent between computers, while IP defines the format or structure of the data sent. TCP/IP also contains advanced security features that make it attractive to security-sensitive organizations and users. This protocol works well in larger networks and slower networks. 94 www.getcoolebook.com Nielsen c05.tex V4 - 07/21/2009 12:19pm Page 95 Client Connectivity 5 With the Configuration Manager, you can enable, disable, and configure these various protocols as appropriate for the operational environment. The utility may be launched from the Start menu by selecting Start ➪ All Programs ➪ Microsoft SQL Server 2008 ➪ Configuration Tools ➪ SQL Server Configuration Manager. The Server Configuration Manager presents a list of all the available protocols and communication options, as shown in Figure 5-1. FIGURE 5-1 The SQL Server Configuration Manager establishes the connectivity protocols used by SQL Server to communicate with clients. All TCP/IP communications is done over a specified port. Well-known ports include HTTP (port 80), FTP (port 21), and SSL (port 443). In most cases, SQL Server communicates over port 1433 when using TCP/IP. If communications are sent through a firewall, this can cause the communication to block. Port 1433 must be opened in a firewall in order for communications to be possible. You can change the port number for instances of SQL Server. In this way, you can map instances to specific TCP/IP ports. When you do this, make sure that there is an opening in the firewall for any ports that you need. Having trouble connecting with your SQL Server? Check these items: ■ Does the server allow remote connections? ■ Do both the server and the client speak the same protocol? ■ Can the client ping the server? ■ Is port 1433 (the SQL Server default port) open on the server’s firewall? ■ Is SQL Browser service running? SQL Native Client Connectivity (SNAC) The SQL Native Client connectivity is managed through the same Server Configuration Manager. SNAC installations will initially default the network protocols to enabling Shared Memory, TCP/IP, and Named Pipes, as shown in Figure 5-2. 95 www.getcoolebook.com Nielsen c05.tex V4 - 07/21/2009 12:19pm Page 96 Part I Laying the Foundation FIGURE 5-2 The SQL Server Configuration Manager view for SQL Native Client Configuration Client Protocols. SNAC also adds support for large User Defined Types (UDT). This enables developers to create custom types of any arbitrary size. In addition, SNAC supports table value parameters. New to 2008 are table- valued parameters, which are used to send multiplerowsofdatatoaT-SQLstatementorroutinewith- out creating multiple other parameters or a temporary table. You declare a table-valued parameter with user-defined table types. There is also a new SNAC OLE DB provider, which offers much better performance. It also makes parameterized queries much more efficient. If SNAC access is not needed or supported by your organization, disabling the appropriate network pro- tocols will reduce your security risks (surface area). SQL Server Native Client Features The development community gains access to the new features of SQL Server 2008 through the SQL Server Native Client (SNAC). If the new features are not needed and managed code is a requirement for data access, then ADO.NET will suffice. While a detailed examination of the features is beyond the scope of this chapter, a summary of each is provided. ADO.NET is an umbrella label applied to the .NET functionality that supports connections to a variety of data sources. Classes within this library supply the programmatic capability to create, maintain, dispose of, and execute actions against a database. For developers, Microsoft Data Access Components (MDAC) is compatible with SQL 2008 but will not be enhanced to support the new 2008 Server features. Because SQL Server Native Client is a component of SQL Server 2008, it must be installed separately on the development machine and must be included with the application setup. Microsoft has included the sqlncli.msi file on the SQL Server installation DVD. This file installs SQL Server Native Client without requiring the full SQL Server installation DVDs. 96 www.getcoolebook.com Nielsen c05.tex V4 - 07/21/2009 12:19pm Page 97 Client Connectivity 5 Requirements The software requirements for installing and running SQL Server Native Client are listed in Table 5-2. The operating system dictates the hardware requirements, including memory, hard disk capacities, CPU, and so on. Chapter 4, ‘‘Installing SQL Server 2008,’’ provides details about SQL Server installation requirements. TABLE 5-2 SNAC Installation Requirements Installer Operating Systems Compatible SQL Server Windows Installer 3.0 Windows XP SP1 or later Windows 2000 Professional Windows 2000 Server Windows 2000 Advanced Server Windows 2000 Datacenter Windows 2003 Server Windows 2003 Enterprise Server Windows 2003 Datacenter Server Windows Vista Windows 2008 Server Windows 2008 Enterprise Server SQL Server 7.0 or later supports connectivity. Asynchronous operations There are times when not waiting on a return from the database call is desirable. It is now possible to open and close a database connection without waiting by setting the appropriate property. Additionally, asynchronous calls returning result sets can be made. In these cases, a valid result set will exist but may still be populating. Therefore, it is necessary to test the asynchronous status of the result set and process it when it is complete. There are some caveats to performing asynchronous operations such as connection pooled objects and use of the cursor’s engine. The asynchronous status is not exposed. Multiple Active Result Sets (MARS) SQL Server 2008 provides support for multiple active SQL statements on the same connection. This capability includes being able to interleave reading from multiple results sets and being able to execute additional commands while a result set is open. Microsoft guidelines for applications using MARS include the following: ■ Result sets should be short-lived per SQL statement. 97 www.getcoolebook.com Nielsen c05.tex V4 - 07/21/2009 12:19pm Page 98 Part I Laying the Foundation ■ If a result set is long-lived or large, then server cursors should be used. ■ Always read to the end of the results and use API/property calls to change connection properties. By default, MARS functionality is not enabled. Turn it on by using a connection string value — MarsConn for the OLE DB provider and Mars_Connection for the ODBC provider. XML data types Much like the current VarChar data type that persists variable character values, a new XML data type persists XML documents and fragments. This type is available for variable declarations within stored pro- cedures, parameter declarations, and return types and conversions. User-defined types These types are defined using .NET common language runtime (CLR) code. This would include the pop- ular C# and VB.NET languages. The data itself is exposed as fields and properties, with the behavior exposed through the class methods. Large value types Three new data types have been introduced to handle values up to 2 ˆ 31-1 bytes long. This includes variables, thus allowing for text values in excess of the old 8K limit. The new types and their corresponding old types are listed in Table 5-3. TABLE 5-3 New SQL Server 2008 Large Values Types New Large Data Types Prior Data Types varchar(max) Text nvarchar(max) ntext varbinary(max) image Handling expired passwords This new feature of SQL Server 2008 enables users to change their expired password at the client with- out the intervention of an administrator. A user’s password may be changed in any of the following ways: ■ Programmatically changing the password such that both the old and new passwords are provided in the connection string ■ A prompt via the user interface to change the password prior to expiration ■ A prompt via the user interface to change the password after expiration 98 www.getcoolebook.com Nielsen c05.tex V4 - 07/21/2009 12:19pm Page 99 Client Connectivity 5 Best Practice I f the old and new passwords are supplied on the connection string, then ensure that this information has not been persisted in some external file. Instead, build it dynamically to mitigate any security concerns. Snapshot isolation The new snapshot isolation feature enhances concurrency and improves performance by avoiding reader- writer blocking. Snapshot isolation relies on the row versioning feature. A transaction begins when the BeginTransaction call is made but is not assigned a sequence transaction number until the first T-SQL statement is executed. The temporary logical copies used to support row versioning are stored in tempdb. If tempdb does not have enough space for the version store, then various features and operations such as triggers, MARS, indexing, client executed T-SQL, and row versioning will fail, so ensure that tempdb has more than enough space for anticipated uses. Summary SQL Server Configuration Manager now provides the server and SQL Native Client protocol manage- ment. SQL Server 2008 supports new features that enrich the client and programmatic data experience. By accessing these new features through the SQL Server Native Client (SNAC), developers are now able to enhance the user experience by providing integrated password changes, improved blocking, and better user interface response with asynchronous calls. In addition, stability increases significantly with the use of mirrored servers and other useful features. 99 www.getcoolebook.com Nielsen c05.tex V4 - 07/21/2009 12:19pm Page 100 www.getcoolebook.com Nielsen c06.tex V4 - 07/21/2009 12:23pm Page 101 Using Management Studio IN THIS CHAPTER A UI worthy of SQL Server 2008 Navigating SQL Server’s objects Organizing projects Maximizing productivity with Query Editor S QL Server’s primary user interface is SQL Server Management Studio (SSMS), a powerful set of tools within a Visual Studio shell that enables the developer or DBA to create database projects and manage SQL Server with either a GUI interface or T-SQL code. For business intelligence (BI) work with Integration Services, Reporting Services, and Analysis Services, there’s a companion tool called SQL Server Business Intelligence Development Studio (BIDS). Like many things in life, Management Studio’s greatest strength is also its great- est weakness. Its numerous tasks, tree nodes, and tools can overwhelm the new user. The windows can dock, float, or become tabbed, so the interface can appear cluttered, without any sense of order. However, once the individual pages are understood, and the interface options mastered, the studios are very flexible, and interfaces can be configured to meet the specific needs of any database task. Personally, I love Management Studio — it’s one of my favorite features of SQL Server 2008. Much of using Management Studio is obvious to experienced IT professionals, and subsequent chapters in this book explain how to accomplish tasks using Management Studio, so I’m not going to explain every feature or menu item in this chapter. Instead, this chapter is a navigational guide to the landscape, pointing out the more interesting features along the way. Management Studio is backwardly compatible, so you can use it to manage SQL Server 2008 and SQL Server 2005 servers. It’s SMO-based, so some features may work with SQL Server 2000, but it’s not guaranteed to be compatible. A common misconception among new SQL Server DBAs is that Management Stu- dio is SQL Server. It’s not. Management Studio is a front-end client tool used to manage SQL Server and develop databases. Typically, Management Studio is run 101 www.getcoolebook.com . manage SQL Server 2008 and SQL Server 2005 servers. It’s SMO-based, so some features may work with SQL Server 2000, but it’s not guaranteed to be compatible. A common misconception among new SQL Server. developers, Microsoft Data Access Components (MDAC) is compatible with SQL 2008 but will not be enhanced to support the new 2008 SQL Server features. Chapter 39, ‘‘Configuring SQL Server, ’’ discusses SQL. developers, Microsoft Data Access Components (MDAC) is compatible with SQL 2008 but will not be enhanced to support the new 2008 Server features. Because SQL Server Native Client is a component of SQL Server