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桂林电子科技大学毕业设计(论文)报告用纸 第 20 页 共 20 页DATABASE MANAGEMENT SYSTEMS（DBMS）AND MANAGEMENT INFORMATION SYSTEM（MIS）You know that a database is a collection of logically related data elements that may be structured in various ways to meet the multiple processing and retrieval needs of organizations and individualsThere s nothing new about databasesearly ones1 were chiseled in stone，penned on scrolls，and written on index cardsBut now databases are commonly recorded on magnetizable media，and computer programs are required to perform the necessary storage and retrieval operationsYoull see in the following pages that complex data relationships and linkages may be found in all but the simplest databases2The system software package that handles the difficult tasks associated with creating，accessing，and maintaining database records is called a database management system（DBMS）The programs in a DBMS package establish an interface between the database itself and the users of the database（These users may be applications programmers，managers and others with information needs，and various OS programs）A DBMS can organize，process，and present selected data elements from the databaseThis capability enables decision makers to search，probe，and query database contents in order to extract answers to nonrecurring and unplanned questions that arent available in regular reports3These questions might initially be vague and / or poorly defined，but people can“browse”through the database until they have the needed informationIn short，the DBMS will“manage”the stored data items and assemble the needed items from the common database in response to the queries of those who arent programmersIn a file-oriented system，users needing special information may communicate their needs to a programmer，who，when time permits，will write one or more programs to extract the data and prepare the information4The availability of a DBMS，however，offers users a much faster alternative communications path.If the DBMS provides a way to interactively and update the database, as well as interrogate it capability allows for managing personal data-Aces however, it does not automatically leave an audit trail of actions and does not provide the kinds of controla necessary in a multiuser organization. These-controls are only available when a set of application programs are customized for each data entry and updating function. Software for personal computers which perform me of the DBMS functions have been very popular arsenal computers were intended for use by individuals for personal information storage and process- These machines have also been used extensively small enterprises, professionals like doctors, acrylics, engineers, lawyers and so on By the nature of. intended usage, database systems on these machines except from several of the requirements of full doge database systemsSince data sharing is not：Tended, concurrent operations even less so, the) fewer can be less complex. Security and integrity7aintenance are de-emphasized or absent. As data-) limes will be small, performance efficiency Is also important. In fact, the only aspect of a database system that is Important is data Independence. Data-.dependence, as stated earlier. Means that applicant programs and user queries need not recognizantphysical organization of data on secondary storage. The importance of this aspect, particularly for the personal computer user, is that this greatly simplifies database usage. The user can store, access and manipulate data at a high level (close to the application) and be totally shielded from the low level (close to the machine) details of data organization. We will not discuss details of specific PC DBMS software packages hereLet us summarize in the following the strengths and weaknesses of personal computer data-base software systems： The most obvious positive factor is the user friendliness of the software. A user with no prior computer background would be able to use the system to store personal and professional data, retrieve and perform relayed processing. The user should, of course, satiety himself about the quality of software and the freedom from errors (bugs) so that invest-merits in data arc protected. For the programmer implementing applications with them, the advantage lies in the support for applications development in terms of input screen generations, output report generation etcoffered by theses stems The main negative point concerns absence of data protection featuresUnless encrypted, data cane accessed by whoever has access to the machine Data can be destroyed through mistakes or maliciousintent. The second weakness of manv of the PC-basedsystems is that of performance. If data volumes growup to a few thousands of records，performance couldbe a bottleneck For organization where growth in data volumesis expected, availability of, the same or compatiblesoftware on large machines should be considered.This is one of the most common misconceptionsabout database management systems that are used inpersonal computersThoroughly comprehensive andsophisticated business systems can be developed indBASh, Paradox and other DBMSsHowever, theyare created by experienced programmers using theDBMSs own programming language. That is not the same as users who create and manage personal filesthat are not part of the mainstream company systemTransaction Management of DatabaseThe objective of long-duration transactions is to model long-duration, interactive Database access sessions in application environmentsThe fundamental assumption about short-duration of transactions that underlies the traditional model of transactions is inappropriate for long-duration transactionsThe implementation of the traditional model of transactions may cause intolerably long waits when transactions aleph to acquire locks before accessing data, and may also cause a large amount of work to be lost when transactions are backed out in response to user-initiated aborts or system failure situations The objective of a transaction model is to pro-vide a rigorous basis for automatically enforcing criterion for database consistency for a set of multiple concurrent read and write accesses to the database in the presence of potential system failure situationsThe consistency criterion adopted for traditional transactions is the notion of scrializabilityScrializa-bility is enforced in conventional database systems through the use of locking for automatic concurrency control, and logging for automatic recovery from system failure situationsA transaction”that doesnt provide a basis for automatically enforcing data-base consistency is not really a transaction. To be sure, a long-duration transaction need not adopt seri-alizability as its consistency criterionHowever. there must be some consistcricv criterionVersion System Management of Database Despite a large number of proposals on version support in the context of computer aided design and software engineering, the absence of a consensus on version semantics has been a key impediment to version support in database systemsBecause of the differences between files and databases, it is intuitively clear that the model of versions in database systems cannot be as simple as that adopted in file systems to support software engineeringFor data-bases, it may be necessary to manage not only versions of single objects (e.g. a software module, document, but also versions of a collection of objects (e.g. a compound document, a user manual，etcand perhaps even versions of the schema of database (c.g. a table or a class, a collection of tables or classes)Broadly, there are three directions of research and development in versioningFirst is the notion of a parameterized versioning，that is, designing and implementing a versioning system whose behavior may be tailored by adjusting system parameters This may be the only viable approach, in view of the fact that there are various plausible choices for virtually every single aspect of versioningThe second is to revisit these plausible choices for every aspect of versioning, with the view to discarding some of themes either impractical or flawed. The third is the investigation into the semantics and implementation of versioning collections of objects and of versioning the database sche There is no consensus of the definition of the term management information system. Some writers prefer alternative terminology such as information processing system, information and decision system, organizational information system, or simply information system to refer to the computer-based information processing system which supports the operations, management, and decision-making functions of an organization. This text uses “MIS” because it is descriptive and generally understood; it also frequently uses “information system” instead of “MIS” to refer to an organizational information system.A definition of a management information system, as the term is generally understood, is an integrated, user-machine system for providing information to support operations, management, and decision-making functions in an organization. The system utilizes computer hardware and software; manual procedures; models for analysis planning, control and decision making; and a database. The fact that it is an integrated system does not mean that it is a single, monolithic structure; rather, it means that the parts fit into an overall design. The elements of the definition are highlighted below. Computer-based user-machine systemConceptually, a management information can exist without computer, but it is the power of the computer which makes MIS feasible. The question is not whether computers should be used in management information system, but the extent to which information use should be computerized. The concept of a user-machine system implies that some tasks are best performed by humans, while others are best done by machine. The user of an MIS is any person responsible for entering input data, instructing the system, or utilizing the information output of the system. For many problems, the user and the computer form a combined system with results obtained through a set of interactions between the computer and the user.User-machine interaction is facilitated by operation in which the users input-output device( usually a visual display terminal) is connected to the computer. The computer can be a personal computer serving only one user or a large computer that serves a number of users through terminals connected by communication lines. The user input-output device permits direct input of data and immediate output of results. For instance, a person using the computer interactively in financial planning poses “what if” questions by entering input at the terminal keyboard; the results are displayed on the screen in a few second.The computer-based user-machine characteristics of an MIS affect the knowledge requirements of both system developer and system user. “computer-based” means that the designer of a management information system must have a knowledge of computers and of their use in processing. The “user-machine” concept means the system designer should also understand the capabilities of humans as system components (as information processors) and the behavior of humans as users of information.Information system applications should not require users to be computer experts. However, users need to be able to specify their information requirements; some understanding of computers, the nature of information, and its use in various management function aids users in this task.Integrated systemManagement information system typically provide the basis for integration of organizational information processing. Individual applications within information systems are developed for and by diverse sets of users. If there are no integrating processes and mechanisms, the individual applications may be inconsistent and incompatible. Data item may be specified differently and may not be compatible across applications that use the same data. There may be redundant development of separate applications when actually a single application could serve more than one need. A user wanting to perform analysis using data from two different applications may find the task very difficult and sometimes impossible.The first step in integration of information system applications is an overall information system plan. Even though application systems are implemented one at a time, their design can be guided by the overall plan, which determines how they fit in with other functions. In essence, the information system is designed as a planed federation of small systems.Information system integration is also achieved through standards, guidelines, and procedures set by the MIS function. The enforcement of such standards and procedures permit diverse applications to share data, meet audit and control requirements, and be shares by multiple users. For instance, an application may be developed to run on a particular small computer. Standards for integration may dictate that the equipment selected be compatible with the centralized database. The trend in information system design is toward separate application processing form the data used to support it. The separate database is the mechanism by which data items are integrated across many applications and made consistently available to a variety of users. The need for a database in MIS is discussed below.Need for a database The term “information” and “data” are frequently used interchangeably; However, information is generally defined as data that is meaningful or useful to the recipient. Data items are therefore the raw material for producing information.The underlying concept of a database is that data needs to be managed in order to be available for processing and have appropriate quality. This data management includes both software and organization. The software to create and manage a database is a database management system.When all access to any use of database is controlled through a database management system, all applications utilizing a particular data item access the same data item which is stored in only one place. A single updating of the data item updates it for all uses. Integration through a database management system requires a central authority for the database. The data can be stored in one central computer or dispersed among several computers; the overriding requirement is that there be an organizational function to exercise control.Utilization of Models It is usually insufficient for human recipients to receive only raw data or even summarized data. Data usually needs to be processed and presented in such a way that the result is directed toward the decision to be made. To do this, processing of data items is based on a decision model. For example, an investment decision relative to new capital expenditures might be processed in terms of a capital expenditure decision model. Decision models can be used to support different stages in the decision-making process. “Intelligence” models can be used to search for problems and/or opportunities. Models can be used to identify and analyze possible solutions. Choice models such as optimization models maybe used to find the most desirable solution.In other words, multiple approaches are needed to meet a variety of decision situations. The following are examples and the type of model that might be included in an MIS to aid in analysis in support of decision-making; in a comprehensive information system, the decision maker has available a set of general models that can be applied to many analysis and decision situations plus a set of very specific models for unique decisions. Similar models are available for planning and control. The set of models is the model base for the MIS.Models are generally most effective when the manager can use interactive dialog to build a plan or to iterate through several decision choices under different conditions.Database Management Systems( 3th Edition ),Wiley ,2004, 5-12A introduction to Database Management SystemRaghu RamakrishnanA database (sometimes spelled data base) is also called an electronic database , referring to any collection of data, or information, that is specially organized for rapid search and retrieval by a computer. Databases are structured to facilitate the storage, retrieval , modification, and deletion of data in conjunction with various data-processing operations .Databases can be stored on magnetic disk or tape, optical disk, or some other secondary storage device.A database consists of a file or a set of files. The information in these files may be broken down into records, each of which consists of one or more fields. Fields are the basic units of data storage , and each field typically contains information pertaining to one aspect or attribute of the entity described by the database . Using keywords and various sorting commands, users can rapidly search , rearrange, group, and select the fields in many records to retrieve or create reports on particular aggregate of data.Complex data relationships and linkages may be found in all but the simplest databases .The system software package that handles the difficult tasks associated with creating ,accessing, and maintaining database records is called a database management system(DBMS).The programs in a DBMS package establish an interface between the database itself and the users of the database. (These users may be applications programmers, managers and others with information needs, and various OS programs.)A DBMS can organize, process, and present selected data elements form the database. This capability enables decision makers to search, probe, and query database contents in order to extract answers to nonrecurring and unplanned questions that arent available in regular reports. These questions might initially be vague and/or poorly defined ,but people can “browse” through the database until they have the needed information. In short, the DBMS will “manage” the stored data items and assemble the needed items from the common database in response to the queries of those who arent programmers.A database management system (DBMS) is composed of three major parts:(1)a storage subsystem that stores and retrieves data in files;(2) a modeling and manipulation subsystem that provides the means with which to organize the data and to add , delete, maintain, and update the data;(3)and an interface between the DBMS and its users. Several major trends are emerging that enhance the value and usefulness of database management systems;Managers: who require more up-to-data information to make effective decisionCustomers: who demand increasingly sophisticated information services and more current information about the status of their orders, invoices, and accounts.Users: who find that they can develop custom applications with database systems in a fraction of the time it takes to use traditional programming languages.Organizations : that discover information has a strategic value; they utilize their database systems to gain an edge over their competitors.The Database ModelA data model describes a way to structure and manipulate the data in a database. The structural part of the model specifies how data should be represented(such as tree, tables, and so on ).The manipulative part of the model specifies the operation with which to add, delete, display, maintain, print, search, select, sort and update the data.Hierarchical Model The first database management systems used a hierarchical model-that is-they arranged records into a tree structure. Some records are root records and all others have unique parent records. The structure of the tree is designed to reflect the order in which the data will be used that is ,the record at the root of a tree will be accessed first, then records one level below the root ,and so on.The hierarchical model was developed because hierarchical relationships are commonly found in business applications. As you have known, an organization char often describes a hierarchical relationship: top management is at the highest level, middle management at lower levels, and operational employees at the lowest levels. Note that within a strict hierarchy, each level of management may have many employees or levels of employees beneath it, but each employee has only one manager. Hierarchical data are characterized by this one-to-many relationship among data.In the hierarchical approach, each relationship must be explicitly defined when the database is created. Each record in a hierarchical database can contain only one key field and only one relationship is allowed between any two fields. This can create a problem because data do not always conform to such a strict hierarchy.Relational Model A major breakthrough in database research occurred in 1970 when E. F. Codd proposed a fundamentally different approach to database management called relational model ,which uses a table as its data structure.The relational database is the most widely used database structure. Data is organized into related tables. Each table is made up of rows called and columns called fields. Each record contains fields of data about some specific item. For example, in a table containing information on employees, a record would contain fields of data such as a persons last name ,first name ,and street address.Structured query language(SQL)is a query language for manipulating data in a relational database .It is nonprocedural or declarative, in which the user need only specify an English-like description that specifies the operation and the described record or combination of records. A query optimizer translates the description into a procedure to perform the database manipulation.Network ModelThe network model creates relationships among data through a linked-list structure in which subordinate records can be linked to more than one parent record. This approach combines records with links, which are called pointers. The pointers are addresses that indicate the location of a record. With the network approach, a subordinate record can be linked to a key record and at the same time itself be a key record linked to other sets of subordinate records. The network mode historically has had a performance advantage over other database models. Today , such performance characteristics are only important in high-volume ,high-speed transaction processing such as automatic teller machine networks or airline reservation system.Both hierarchical and network databases are application specific. If a new application is developed ,maintaining the consistency of databases in different applications can be very difficult. For example, suppose a new pension application is developed .The data are the same, but a new database must be created.Object Model The newest approach to database management uses an object model , in which records are represented by entities called objects that can both store data and provide methods or procedures to perform specific tasks.The query language used for the object model is the same object-oriented programming language used to develop the database application .This can create problems because there is no simple , uniform query language such as SQL . The object model is relatively new, and only a few examples of object-oriented database exist. It has attracted attention because developers who choose an object-oriented programming language want a database based on an object-oriented model.Distributed DatabaseSimilarly , a distributed database is one in which different parts of the database reside on physically separated computers . One goal of distributed databases is the access of information without regard to where the data might be stored. Keeping in mind that once the users and their data are separated , the communication and networking concepts come into play .Distributed databases require software that resides partially in the larger computer. This software bridges the gap between personal and large computers and resolves the problems of incompatible data formats. Ideally, it would make the mainframe databases appear to be large libraries of information, with most of the processing accomplished on the personal computer.A drawback to some distributed systems is that they are often based on what is called a mainframe-entire model , in which the larger host computer is seen as the master and the terminal or personal computer is seen as a slave. There are some advantages to this approach . With databases under centralized control , many of the problems of data integrity that we mentioned earlier are solved . But todays personal computers, departmental computers, and distributed processing require computers and their applications to communicate with each other on a more equal or peer-to-peer basis. In a database, the client/server model provides the framework for distributing databases.One way to take advantage of many connected computers running database applications is to distribute the application into cooperating parts that are independent of one anther. A client is an end user or computer program that requests resources across a network. A server is a computer running software that fulfills those requests across a network . When the resources are data in a database ,the client/server model provides the framework for distributing database.A file serve is software that provides access to files across a network. A dedicated file server is a single computer dedicated to being a file server. This is useful ,for example ,if the files are large and require fast access .In such cases, a minicomputer or mainframe would be used as a file server. A distributed file server spreads the files around on individual computers instead of placing them on one dedicated computer.Advantages of the latter server include the ability to store and retrieve files on other computers and the elimination of duplicate files on each computer. A major disadvantage , however, is that individual read/write requests are being moved across the network and problems can arise when updating files. Suppose a user requests a record from a file and changes it while another user requests the same record and changes it too. The solution to this problems called record locking, which means that the first request makes others requests wait until the first request is satisfied . Other users may be able to read the record, but they will not be able to change it .A database server is software that services requests to a database across a network. For example, suppose a user types in a query for data on his or her personal computer . If the application is designed with the client/server model in mind ,the query language part on the personal computer simple sends the query across the network to the database server and requests to be notified when the data are found.Examples of distributed database systems can be found in the engineering world. Suns Network Filing System(NFS),for example, is used in computer-aided engineering applications to distribute data among the hard disks in a network of Sun workstation.Distributing databases is an evolutionary step because it is logical that data should exist at the location where they are being used . Departmental computers within a large corporation ,for example, should have data reside locally , yet those data should be accessible by authorized corporate management when they want to consolidate departmental data . DBMS software will protect the security and integrity of the database , and the distributed database will appear to its users as no different from the non-distributed database .How to troubleshoot connectivity issues in SQL Server 2000Chris Tull, Microsoft Help and SupportThis article can help you to resolve connectivity problems with Microsoft SQL Server 2000. This article contains descriptions of common connectivity problems and the steps that you can take to help resolve your connectivity problems. SQL Server 2000 supports several methods of communication between the instance of SQL Server and the client applications. If your client application and the instance of SQL Server reside on the same computer, Microsoft Windows interprocess communication (IPC) components, such as local named pipes or the Shared Memory protocol, are used to communicate. However, when the client application and the instance of SQL Server reside on different computers, a network IPC, such as TCP/IP or named pipes, is used to communicate.SQL Server 2000 uses Net-Library, a DLL, to communicate with a particular network protocol. A matching pair of Net-Libraries must be active on the client computer and the server computer to support the network protocol that you want to use. For example, if you want to enable a client application to communicate with a specific instance of SQL Server across TCP/IP, the client TCP/IP Sockets Net-Library (Dbnetlib.dll) must be configured to connect to the server on the client computer. Likewise, the server TCP/IP Sockets Net-Library (Ssnetlib.dll) must listen on the server computer. In this scenario, the TCP/IP protocol stack must be installed on both the client computer and the server computer.After you install SQL Server 2000, you can configure the properties of the client Net-Libraries by using Client Network Utility. You can configure the properties of the server Net-Libraries by using Server Network Utility (Svrnetcn.exe). The server Net-Libraries are installed during the installation of the server tools in SQL Server Setup. However, some of the server Net-Libraries may not be active. By default, SQL Server 2000 enables and listens on TCP/IP, named pipes, and Shared Memory. Therefore, for a client to connect to a server computer, the client must connect by using a client Net-Library that matches one of the server Net-Libraries that is currently being used by the instance of SQL Server.For additional information about SQL Server communication components and Net-Libraries, see the following topics in SQL Server Books Online: Communication ComponentsClient and Server Net-LibrariesManaging ClientsTroubleshoot connectivity issuesMost of the connectivity issues that you may notice in SQL Server 2000 occur because of problems with TCP/IP, Windows authentication, or a combination of TCP/IP and Windows authentication. Important Before you start to troubleshoot connectivity issues in SQL Server 2000, make sure that the MSSQLServer service is started on the computer that is running SQL Server.Verify your DNS settingsThe name resolution process in Domain Name System (DNS) is used to resolve the IP address to the name of the instance of SQL Server. If the name resolution process does not work correctly, the instance of SQL Server is not reachable, and you may receive one or more of the following error messages: SQL Server does not exist or access deniedGeneral Network ErrorCannot Generate SSPI ContextTo verify that the name resolution process is resolving the correct server, you can ping the server by using the server name and the IP address of the server. To do so, follow these steps: 1.Click Start, and then click Run.2.In the Run dialog box, type cmd in the Open box, and then click OK.3.At the command prompt, run the following command:ping Note the IP address that is returned.4.At the command prompt, run the following command (where IP address is the IP address that you noted in step 3):ping a Verify that the command resolves to the correct server name. If either of the specified commands are not successful, time out, or do not return the correct values, the DNS lookup is not working correctly or the problem occurs because of other networking or routing issues. To see your current DNS settings, run the following command at a command prompt:ipconfig /allTo work around this problem, add an entry for the server to the %systemroot%system32driversetchosts file on the client computer. You can also work around the problem by connecting to the server by using the Named Pipes Net-library.Verify the enabled protocols and aliasesConnectivity problems may occur if the alias on the client computer is set incorrectly. You can view the aliases by using Client Network Utility. To do so, follow these steps: 1.Start Client Network Utility. If the SQL Server client tools are installed on the computer that is running the client application, follow these steps to start Client Network Utility: a. Click Start, and then point to Programs.b. Point to Microsoft SQL Server, and then click Client Network Utility.If the SQL Server client tools are not installed on the client computer, follow these steps to start Client Network Utility: a. Click Start, and then click Run.b. In the Run dialog box, type cliconfg in the Open box, and then click OK.2.In the SQL Server Client Network Utility window, click the General tab, and then enable all the protocols that you want to use.Note You must at least enable the TCP/IP protocol and the named pipes protocol.3.Click the Alias tab, and then verify the aliases that are configured for the instance of SQL Server. 4.Verify the properties of the aliases to make sure that the server name or IP address and the protocol are configured correctly.You can create a new alias to test the connectivity by using the server name, the IP address, or even by using a different protocol.Note Earlier versions of Microsoft Data Access Components (MDAC) have a different user interface for Client Network Utility. Therefore, if you do not see the options that are listed in this article, install a later version of MDAC on the computer that is running the client application.Verify that the instance of SQL Server is listening correctlyTo verify that the instance of SQL Server is listening on named pipes, TCP/IP, or another protocol that you are using at the client application, open the current SQL Server error log file. The SQL Server error log file may contain entries that are similar to the following:2003-11-06 09:49:36.17 server SQL server listening on TCP, Shared Memory, Named Pipes. 2003-11-06 09:49:36.17 server SQL server listening on :1433, :1433.If you analyze the entries in the SQL Server error log file, you can verify that the instance of SQL Server is listening on the correct IP address and on the correct port. By default, a default instance of SQL Server listens on the port 1433. You can also use Server Network Utility to verify the protocol settings for SQL Server and to change the properties in SQL Server, including the protocols that can connect to SQL Server and the ports that can be used. For more information about using Server Network Utility, see the SQL Server Network Utility topic in SQL Server Books Online. Sometimes, SQL Server 2000 may not bind to port 1433 or any other specified port. This problem may occur if the port is being used by another application or if you are trying to connect by using an IP address that is not correct. Therefore, the TCP/IP connections to SQL Server may not be successful and you may receive the following error message in the SQL Server error log file: 2001-11-14 15:49:14.12 server SuperSocket Info: Bind failed on TCP port 1433.If you cannot connect to the instance of SQL Server by using a TCP/IP connection, try to use the named pipes protocol or the Shared Memory protocol. Run the following command at a command prompt to obtain information about the ports that are in use:NETSTAT anYou can also use the Portqry command-line utility to obtain more information about the ports that are in use.Note For named instances of SQL Server, SQL Server dynamically determines the port and listens on the determined port. Therefore, when you start the named instance of SQL Server, SQL Server tries to listen on the port that was previously being used. If SQL Server cannot bind to that port, the named instance may dynamically bind to a different port. In that situation, make sure that the client application is also set to determine the port dynamically. Alternatively, you can also specify a static port for the named instance to bind to and to listen on by using Client Network Utility.Troubleshoot MDAC IssuesConnectivity problems may also occur because of problems with MDAC. For example, a software installation may overwrite some of the MDAC files or change the permissions that you must have to access the MDAC files. You can run the MDAC Component Checker to verify the MDAC installation on your computer.Note If you are connecting to a named instance of SQL Server, make sure that you are running MDAC 2.6 or later on your computer. Earlier versions of MDAC do not recognize named instances of SQL Server. Therefore, connections to named instances may not be successful.You can use the Odbcping.exe utility to verify connections through the SQL Server ODBC driver.You can also test connectivity to the instance of SQL Server by using a .udl file.Troubleshoot firewall issuesIf firewall exists between the client computer and the computer that is running SQL Server, make sure that the ports that are required to communicate through the firewall are open.If you use the TCP/IP protocol to connect to the instance of SQL Server, make sure that you can use the Telnet program to connect to the port where SQL Server is listening. To use the Telnet program, run the following command at a command prompt: Telnet If the Telnet program is not successful and you receive an error message, resolve the error and then try to connect again.Note Because of issues that were caused by the Slammer virus, the User Datagram Protocol (UDP) port 1434 may be blocked on your firewall.Troubleshoot authentication and security issuesConnections to SQL Server may not be successful because of authentication failures. If the authentication fails, you may receive one of the following error messages:Login failed for user Login failed for user NTAUTHORITYANONYMOUS LOGONLogin failed for user nullIf you receive an error message because of an authentication failure and the error message does not mention a specific SQL Server login name, troubleshoot the problem with Windows authentication. You may receive the following error message because of problems with Windows authentication: Cannot generate SSPI ContextThe following problems may cause authentication and security issues: Problems occur with NTLM authentication or with Kerberos authentication.The domain controller cannot be contacted because of connectivity issues.Problems occur with trust relationships across domains.For more information about possible causes, see the event logs on the computer. To work around connectivity problems with Windows authentication, you can use SQL Server Authentication to connect to the instance of SQL Server. If the connection is not successful when you use SQL Server Authentication, you receive the following error message: Login failed for user . Not associated with a trusted connectionTo troubleshoot this problem, follow these steps. Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk. 1.Make sure that the instance of SQL Server is configured to use Windows authentication and SQL Server Authentication. To do so, make sure that the following registry keys are on the computer that is running SQL Server. For the default instance of SQL Server: HKEY_LOCAL_MACHINESoftwareMicrosoftMSSQLServerMSSQLServerLoginModeFor the named instance of SQL Server: HKEY_LOCAL_MACHINESoftwareMicrosoftMicrosoft SQL ServerMSSQLServerLoginModeMake sure that the following registry key values are set:Authentication typeValueWindows authentication only1Mixed mode (SQL Server Authentication and Windows authentication)2Note If you make any changes to the registry, you must stop and then restart the instance of SQL Server for the changes to take effect.2.Try to connect to the instance of SQL Server by using different Windows accounts or SQL Server login accounts. This can help determine if the connection is not successful because of problems with a particular login account. For example, the password of the login account may have been changed.3.Try to connect to the instance of SQL Server by using different protocols. For example, the connections that use the TCP/IP protocol with Windows authentication may not be successful, but connections that use the named pipes protocol with Windows authentication may be successful.If you are using certificates, you may receive a Secure Sockets Layer (SSL) security error message when you try to connect to the instance of SQL Server. Troubleshoot stress on TCP/IP socketsWhen you use the SQL Server ODBC driver, the Microsoft OLE DB Provider for SQL Server, or the System.Data.SqlClient managed provider, you can disable connection pooling by using the appropriate application programming interfaces (APIs). When you disable connection pooling and your application frequently opens and closes connections, the stress on the underlying SQL Server network library may increase. Sometimes, the Web servers and the JDBC drivers may also try to connect to the instance of SQL Server. Therefore, the increase in connection requests to SQL Server may be more than SQL Server can handle. This may stress the TCP/IP sockets, and you may receive the following error message in the SQL Server error log file: 2003-08-07 20:46:21.11 server Error: 17832, Severity: 20, State: 6 2003-08-07 20:46:21.11 server Connection opened but invalid login packet(s) sent. Connection closed.For additional information, click the following article numbers to view the articles in the Microsoft Knowledge Base: 154628 (/kb/154628/) INF: SQL logs 17832 with multiple TCPIP connection requests 328476 (/kb/328476/) TCP/IP settings for SQL Server drivers when pooling is disabled Note You may not notice the stress on TCP/IP sockets if you are running SQL Server 2000 SP3 or SQL Server 2000 SP3a because a limit on the number of login packets was added. The 17832 error occurs when you use third-party drivers to connect to the instance of SQL Server. To resolve this problem, contact the third-party ve
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