Hướng dẫn học Microsoft SQL Server 2008 part 14 pdf

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Client Connectivity
IN THIS CHAPTER
Enabling server connectivity
SQL Native Client development
features
Client software connectivity
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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.
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Part I Laying the Foundation
What’s New in 2008 Connectivity
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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.
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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.
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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.
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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.
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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
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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.
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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
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