rfc677.The Maintenance of Duplicate Databases
数据库兼容性问题的解决方案
数据库兼容性问题的解决方案在当今信息技术快速发展的时代，数据库管理系统扮演着非常重要的角色。
不同数据库管理系统之间的兼容性问题经常困扰着数据库管理员和开发人员。
这些问题可能导致数据丢失、应用程序错误等严重后果。
为了解决这些兼容性问题，我们可以采取以下几种方案。
1. 数据库迁移工具：数据库迁移工具是一种常见的用于解决数据库兼容性问题的解决方案。
这些工具可以将一个数据库系统中的数据和结构迁移到另一个数据库系统中。
例如，当从MySQL迁移到Oracle时，可以使用MySQL Workbench或Data Pump实用程序将数据转换为相应的Oracle格式。
通过使用数据库迁移工具，可以减少兼容性问题带来的风险，并将数据库顺利迁移到新的环境中。
2. 标准化SQL语法：不同的数据库管理系统对SQL语法有不同的实现细节和扩展功能。
为了解决这个问题，我们可以采用标准化的SQL语法编写应用程序或查询。
ANSI SQL是一种被广泛接受的标准SQL语法。
通过使用标准化的SQL语法，可以最大限度地减少兼容性问题，并使应用程序在不同的数据库管理系统上运行更加稳定。
3. 抽象数据库层：抽象数据库层是一种将应用程序与底层数据库管理系统解耦的技术。
通过在应用程序和数据库之间引入一个抽象层，可以将数据库兼容性问题从应用程序中隔离出来。
应用程序只需与抽象层进行交互，而不需关心底层数据库的具体实现。
ORM（对象关系映射）工具如Hibernate和Entity Framework等可以帮助我们实现这种抽象数据库层。
通过使用抽象数据库层，我们可以在不同的数据库管理系统之间切换，而不需要修改应用程序的代码。
4. 定期数据库备份和恢复：数据库备份是一种重要的解决兼容性问题的策略。
通过定期备份数据库，可以确保在发生兼容性问题时，可以快速恢复到之前的状态。
备份文件可以在不同的数据库管理系统之间进行导入和导出，从而解决兼容性问题。
此外，值得注意的是，备份文件的格式和版本也需要考虑，以确保它们与目标数据库兼容。
FIN-AR
Customer account managers provided with up to date credit status
Treasury policy set on late and prompt payments
Authority levels clearly defined
Credit policies defined and agreed
Terms and conditions agreed with customers
Sales orders prepared using pricing database with pricing profiles for products and customers
6
Accounts Receivable - Measures/Cost Drivers
Number of customer payment received per accounts receivableAccounts receivable cost per sales invoice processed FTE per annum £3
To provide complete forecast information to assist the management of short-term cash requirements
2
People
Customer relations Legal framework
awareness Credit management
System Features
SOP linked to debtors ledger to ensure customer credit limits not exceeded
sqlserver错误号大全
sqlserver错误号⼤全0 操作成功完成。
1 功能错误。
2 系统找不到指定的⽂件。
3 系统找不到指定的路径。
4 系统⽆法打开⽂件。
5 拒绝访问。
6 句柄⽆效。
7 存储控制块被损坏。
8 存储空间不⾜，⽆法处理此命令。
9 存储控制块地址⽆效。
10 环境错误。
11 试图加载格式错误的程序。
12 访问码⽆效。
13 数据⽆效。
14 存储器不⾜，⽆法完成此操作。
15 系统找不到指定的驱动器。
16 ⽆法删除⽬录。
17 系统⽆法将⽂件移到不同的驱动器。
18 没有更多⽂件。
19 介质受写⼊保护。
20 系统找不到指定的设备。
21 设备未就绪。
22 设备不识别此命令。
23 数据错误 (循环冗余检查)。
24 程序发出命令，但命令长度不正确。
25 驱动器⽆法找出磁盘上特定区域或磁道的位置。
26 ⽆法访问指定的磁盘或软盘。
27 驱动器找不到请求的扇区。
28 打印机缺纸。
29 系统⽆法写⼊指定的设备。
30 系统⽆法从指定的设备上读取。
31 连到系统上的设备没有发挥作⽤。
32 进程⽆法访问⽂件，因为另⼀个程序正在使⽤此⽂件。
33 进程⽆法访问⽂件，因为另⼀个程序已锁定⽂件的⼀部分。
36 ⽤来共享的打开⽂件过多。
38 到达⽂件结尾。
39 磁盘已满。
50 不⽀持⽹络请求。
51 远程计算机不可⽤。
52 在⽹络上已有重复的名称。
53 找不到⽹络路径。
54 ⽹络忙。
55 指定的⽹络资源或设备不再可⽤。
56 已到达⽹络 BIOS 命令限制。
57 ⽹络适配器硬件出错。
58 指定的服务器⽆法运⾏请求的操作。
59 发⽣意外的⽹络错误。
60 远程适配器不兼容。
61 打印机队列已满。
62 ⽆法在服务器上获得⽤于保存待打印⽂件的空间。
63 删除等候打印的⽂件。
64 指定的⽹络名不再可⽤。
65 拒绝⽹络访问。
66 ⽹络资源类型错误。
67 找不到⽹络名。
68 超过本地计算机⽹卡的名称限制。
69 超出⽹络 BIOS 会话限制。
70 远程服务器已暂停，或正在启动过程中。
SecureOSPF English
Who's watching your network
Routing Protocols
characterized by applicable area
– intra-AS: within one Autonomous System – inter-AS: between Autonomous System
6/21/2000 12
Who's watching your network
Key Management
assume the existence of a Trusted Entity introduce new LSA called Public Key LSA (PKLSA)
– holds router's key – signed by Trusted Entity
6/21/2000
1
Who's watching your network
Risks from Bad Routing Information
sub-optimal routing partition congestion in parts of the network overwhelmed hosts non-delivery due to packet looping access to transmitted data
6/21/2000 18
�
Who's watching your network
OSPF Events
hello protocol establishes neighbors synchronize Link State Advertisement (LSA) databases periodic re-issue of information in Link State Advertisements duplicate LSA's distinguished by sequence number and age
处理数据库置疑的方法
处理数据库置疑的方法处理数据库置疑的方法先分离数据库企业管理器--右键置疑的数据库--所有任务--分离数据库然后备份你的置疑数据库的文件,再按下面的步骤处理:1.新建一个同名的数据库2.再停掉sql server3.用置疑数据库的文件覆盖掉这个新建的同名数据库，只覆盖mdf文件，日志文件不要覆盖4.再重启sql server5.此时打开企业管理器时新建的同名数据库会出现置疑，先不管，打开查询分析器执行下面的语句（注意修改其中的数据库名)重建日志文件，经过修复后数据就可以正常分离并附加了，语句中“C:\置疑的同名数据库名_Log.ldf”是重建日志日志文件存放路径，在重建日志后，最好将数据库分离并将重新创建的日志文件拷贝到数据库文件所在目录，再重新进行附加。
--重建日志文件，修复损坏的日志USE MASTERSP___RE 'ALLOW __',1 __GURE WITH __EGOUPDATE __BASES SET STATUS =__ WHERE NAME='置疑的同名数据库名'Godbcc rebuild_log('置疑的同名数据库名','C:\置疑的同名数据库名_Log.ldf')GOupdate sysdatabases set status =28 where name='置疑的同名数据库名'Gosp_configure 'allow updates', 0 reconfigure with overrideGo6、数据库修复后还需要进行数据库检测，看是否存在一些错误，数据库检测需要用DBCC __命令，如下：DBCC __('置疑的同名数据库名')如果检测到错误，需要进行修复，但修复数据库需要在单用户模式下，请使用以下语句,ALTER __E 置疑的同名数据库名SET SINGLE_USER WITH __K __TEDBCC __ ('置疑的同名数据库名',REPAIR___)GOALTER __E 置疑的同名数据库名SET MULTI_USER WITH __K __TEGO如果还有错误，执行下面的语句DBCC __ ('数据库名',REPAIR_ALLOW_DATA_LOSS )-------(执行一次如果还有错误，可以多执行几次)7、有时通过DBCC __能够修复数据库中的错误，但有时不能修复，可能需要对单个有问题的数据表进行修复，需要使用DBCC __BLE('有问题的数据表名',REPAIR___) 命令，详细请看联机帮助8、DBCC __命令介绍检查指定数据库中的所有对象的分配和结构完整性。
Accounts Payable.ppt
Measures
Speed of processing supplier amendments Invoices processed Invoice processing time Number of payments Period end closure time
PwC175b(1)
3
Accounts Payable - Best practice features
Number of purchase invoices per FTE per annum 15,000 7,000 3,000 or less £2 £17 10 percentile 90 percentile Median 10 percentile 90 percentile Median Cost drivers Number of invoices received per month Number of suppliers Number of different terms and conditions Complexity of authorisation process Proportion of invoices automatically matched with PO's Number of supplier queries Proportion of invoices received electronically Proportion of payments made electronically Cost per purchase invoice processed £6
Accounts Payable Objectives
To maximise processing efficiency To ensure invoices are processed to agreed terms To ensure payments made only when due and payable To ensure liabilities are fully recorded and distributed correctly To achieve effective balance between extending credit and maintaining good relations with suppliers To take full advantage of opportunities to recover VAT
duplicate entry for key 用法
duplicate entry for key 用法Duplicate entry for key是MySQL数据库中常见的错误提示，意思是在插入或更新数据时，发现有重复的键值，导致操作失败。
这个错误提示通常会伴随着一个具体的键名，帮助我们定位到具体的冲突数据。
那么，如何避免这个错误呢？以下是几个建议：1. 设计合理的数据库结构在设计数据库时，应该合理规划表结构和索引，避免出现重复的键值。
例如，在用户表中，应该将用户名设置为唯一索引，这样就可以避免出现重复的用户名。
2. 在插入或更新数据前进行检查在插入或更新数据前，可以先查询数据库中是否已经存在相同的键值，如果存在，则不进行操作。
这样可以避免出现重复的键值。
3. 使用ON DUPLICATE KEY UPDATE语句在插入数据时，可以使用ON DUPLICATE KEY UPDATE语句，当发现重复的键值时，可以更新已有数据。
例如：INSERT INTO user (id, name, age) VALUES (1, 'Tom', 18) ON DUPLICATE KEY UPDATE name='Tom', age=18;如果id为1的用户已经存在，则会更新该用户的姓名和年龄，否则会插入一条新的数据。
4. 使用IGNORE关键字在插入数据时，可以使用IGNORE关键字，当发现重复的键值时，会忽略该条数据。
例如：INSERT IGNORE INTO user (id, name, age) VALUES (1, 'Tom', 18);如果id为1的用户已经存在，则会忽略该条数据，不会进行插入操作。
总之，避免出现duplicate entry for key错误的关键在于合理规划数据库结构和索引，以及在操作前进行检查和使用合适的语句。
当然，在出现错误时，我们也应该及时排查问题，找到具体的冲突数据并进行处理。
JD Edwards EnterpriseOne 实业管理软件说明书
JD Edwards EnterpriseOneReal Estate ManagementInvestment and commercial real estate operations today need comprehensive, timely, and accurate data to be competitive and more profitable. You want better information to manage properties more efficiently and streamline your interactions with tenants, managers, lenders, and owners. JD Edwards EnterpriseOne Real Estate Management integrates your real estate operation so that you are more involved with managing investments rather than paperwork and data.K E Y F E A T U R E S•Pre-integrated for use with all JD Edwards EnterpriseOne applications •Monitor occupancy and cash flow rates•Complete tenant and lease administration•Occupancy analysis•Global lease updates•Common area maintenance caps and exclusion rules•Common area maintenance billings •Robust Expense Participation functionality•Sales forecasting and inquiries •Sales overage billings •Escalations (CPI) billings•Manual and recurring billings •Security deposits•Tenant work orders•Holdover processing •Management fees and late fees •Straight-line rent accounting and reporting•Revenue recognition•Balance sheet lessee accounting for property and non-property assets The Issue: Developing and Keeping a Competitive EdgeInvestors and tenants want to make smart decisions regarding their investments. To attract investors and tenants, real estate organizations need a competitive edge. The right properties, appealing returns, and an efficient way to manage and maintain those facilities are required to be successful in this increasingly competitive market.Many real estate organizations use time-consuming processes, including managing disparate databases and technologies, which results in executives spending time managing data instead of managing their investments.Current, accurate, easily-accessible information is critical. Your competitive advantage becomes stronger when you have the latest information on occupancy patterns, property data, and market information from a single data source. Most important, real-time visibility across your portfolio helps promote operational efficiencies and higher return on investment.The Solution: Integrated Data and Information in One SolutionOracle’s JD Edwards EnterpriseOne Real Estate Management integrates all cri tical information to effectively manage real property investments. Whether you are an owner, landlord, tenant/lessee, or all of the above, this solution lets you streamline your financial and operational processes, allowing you to manage properties more effectively.Real Estate Management enables you to constantly monitor the factors that affect your portfolio, from accounts payable and receivable to lease origination and occupancy patterns. Integration with JD Edwards EnterpriseOne Service Billing and JD Edwards EnterpriseOne Accounts Receivable can help improve cash flow by reducing the time required to bill, collect, and record receivables. Integration with JD Edwards EnterpriseOne Fixed Assets enables you to account for lessee leases of both property and non-property assets.F E A T U R E/F U N C T I O N H IGH LI G H T S •Projected rents•Critical date reporting•Lease option and legal clause tracking•Point-in-time reporting Improving Cash FlowWhen you increase the speed and accuracy of the bill-to-pay process, you stimulate cash flow. By automating the complex task of calculating expense participation and rent, comprehensive tenant statements are prepared and delivered faster with greater accuracy, resulting in improved cash flow. The JD Edwards EnterpriseOne Real Estate Management solution streamlines your cash management by:Executing multiple types of billings, such as manual and recurring invoices.Prorating any billing or calculating “catch up” billings .Providing user-defined billing methods for expense participation or commonarea maintenance, escalations, percentage rent, and special concessions.Excluding unique tenant contributions or calculating administration fees ontotal expenses before anchor and other exclusions.Automating fee calculations, security deposit processing, late fees, andinterest calculations.Expense Participation (EP) provides robust capabilities for setup and management of expense allocation, enabling users to handle complex expense scenarios, including distinguishing between physical and economic occupancy. The system handles adjustment factors, exclusions, redistribution calculations at class, account, and lease levels to accurately recognize intricate expense and lease-level caps. Full audit and drill-down capabilities facilitate understanding of the various calculations for EP generation. EP features enable users to easily set up expense participation classes and provide critical information to ensure higher accuracy and profitability.Positioning for GrowthReal Estate Management is a scalable solution that can handle significant growth in portfolio size with little effect on overhead costs and resource requirements. The solution easily accommodates growth in the number of properties, leases, and billing transactions. Whether acquiring existing space or the developing new properties, the system can handle the volume of your growing portfolio with a single database.Increasing Occupancy RatesHaving the right space at the right time is key to increasing occupancy rates. Prospective customers who are looking for space require quick and accurate answers. Quickly addressing your prospective customer requirements helps drive higher occupancy rates. Web access to space availability facilitates critical dynamic intelligence for the leasing community. Users can isolate vacancies by property, date ranges, and square footage.Critical expiration date alerts enable property managers to proactively promote available space to maximize occupancy rates.Improving ProductivityJD Edwards EnterpriseOne Real Estate Management uses collaborative portal technology to extend your enterprise over the web in real time, enabling tenants, lenders, owners, and facility managers to access property information any time.Additionally, a single-source, integrated solution eliminates duplicate data entry, provides real-time access and reporting across the entire portfolio, and reduces time spent reconciling data from disparate systems.You can also add JD Edwards EnterpriseOne Advanced Real Estate Forecasting. This product greatly expands the JD Edwards EnterpriseOne solution and dramatically reduces budgeting and forecasting cycles. Multiple economic scenarios can be easily modeled to investigate the effect on net operating income and property valuation. Budgeting and forecasting capabilities are seamlessly incorporated with core financial components of JD Edwards, ensuring information integrity.Additional productivity features in the Real Estate Management system include: Easily import the terms and conditions of your leases from a csv (comma-separated value) flat file into EnterpriseOne using Z table processing.Automatically create asset master records from the Real Estate ManagementUnit Master for balance sheet accounting purposes.Use dashboard capabilities of UX One landing pages for several Real EstateManagement roles.Minimized errors by specifying default values for leases and billing records.Produce accurate financial reports using Revenue Recognition and Straight-line Rent (FASB 13).Streamline lease administration and balance sheet lessee accounting for bothproperty and non-property assets.Shorten month-end close process with automatic monthly adjusting balancesheet journal entries that generate an audit trail. Additionally, use an alternateset of amortization schedules to report financial information to an entity, suchas a parent company, that reports financial information under a differentstandard (US GAAP vs. IFRS).Minimize errors using features that automate updates to recurring payments,amortization schedules, and financial accounts, when the terms of a leasechange.Improve operational efficiency for lessees of assets using the simplified lesseeLease Master forms, grids, and Café One personalizations.Solution IntegrationThis module is designed to integrate with these JD Edwards EnterpriseOne products and suites across your operations using common tools and a Pure Internet Architecture:JD Edwards EnterpriseOne Advanced Real Estate ForecastingJD Edwards EnterpriseOne Financial Management system, including GeneralAccounting, Accounts Payable, and Accounts ReceivableJD Edwards EnterpriseOne Fixed AssetsJD Edwards EnterpriseOne Project ManagementJD Edwards EnterpriseOne Service and Contract BillingJD Edwards EnterpriseOne Inventory ManagementJD Edwards EnterpriseOne Procurement ManagementJD Edwards EnterpriseOne Subcontract ManagementO R A C L E D A T A S H E E TC O N T A C T U SFor more information about JD Edwards EnterpriseOne, visit or call +1.800.ORACLE1 tospeak to an Oracle representative.C O N N E C T W I T H U S/oracle/oracle/oracleCopyright © 2018, Oracle and/or its affiliates. All rights reserved. This document is provided for information purposes only, and thecontents hereof are subject to change without notice. This document is not warranted to be error-free, nor subject to any otherwarranties or conditions, whether expressed orally or implied in law, including implied warranties and conditions of merchantability orfitness for a particular purpose. We specifically disclaim any liability with respect to this document, and no contractual obligations areformed either directly or indirectly by this document. This document may not be reproduced or transmitted in any form or by any means,electronic or mechanical, for any purpose, without our prior written permission.Oracle and Java are registered trademarks of Oracle and/or its affiliates. Other names may be trademarks of their respective owners.Intel and Intel Xeon are trademarks or registered trademarks of Intel Corporation. All SPARC trademarks are used under license andare trademarks or registered trademarks of SPARC International, Inc. AMD, Opteron, the AMD logo, and the AMD Opteron logo are。
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Network Working Group Paul R. Johnson (BBN-TENEX)RFC # 677 Robert H. Thomas (BBN-TENEX)NIC # 31507 January 27, 1975
The Maintenance of Duplicate DatabasesPreface:This RFC is a working paper on the problem of maintaining duplicateddatabases in an ARPA-like network. It briefly discusses the generalduplicate database problem, and then outlines in some detail a solutionfor a particular type of duplicate database. The concepts developedhere were used in the design of the User Identification Database for theTIP user authentication and accounting system. We believe that theseconcepts are generally applicable to distributed database problems.
Johnson & Thomas [Page 1]RFC 677 The Maintenance of Duplicate Databases January 1975Introduction There are a number of motivations for maintaining redundant,duplicate copies of databases in a distributed network environment. Twoimportant motivations are:
- to increase reliability of data access. The accessibility of critical data can be increased by redundantly maintaining it. The database used for TIP login and accounting is redundantly distributed to achieve highly reliable access.
- to insure efficiency of data access. Data can be more quickly and efficiently accessed when it is "near" the accessing process. A copy of the TIP user ID database is maintained at each site supporting the TIP login service to insure rapid, efficient access. (Reliability considerations dictate that this database be redundantly maintained, and efficiency considerations dictate that a copy be maintained at each authentication site.)
The design of a system to maintain redundant, duplicate databases isa challenging task because of the inherent communication delay betweencopies of the database, as well as the real world constraints of systemcrashes, operator error, communication channel failure, etc. This paperdiscusses some of the problems we encountered in designing such asystem, and outlines a system design for maintaining a particular typeof database which solves those problems.
The Model A system for supporting duplicate copies of a database can bemodeled by a group of independent database management processes (DBMPs)each maintaining its own copy of the database. These processescommunicate with each other over network communication paths. Each DBMPhas complete control over its copy of the database. It handles allaccesses to and modifications of the database in response to requestsfrom other processes. Though the DBMPs act only upon requests, in thefollowing they will often be said to be actually causing or originatingthe modifications.
An important design consideration is that the communication pathsbetween the DBMPs are subject to failures. Thus one DBMP may have itsinteractions with other DBMPs interrupted and/or have to wait untilcommunication paths are re-established before it can communicate withother DBMPs. An assumption made in this paper about the communication
Johnson & Thomas [Page 2]RFC 677 The Maintenance of Duplicate Databases January 1975paths is that messages from one process to another are delivered in thesame order that they are sent. This is true of the ARPANET. For networksthat make no such guarantee, communication protocols between the DBMPscan be used to correctly order the messages.
In order to proceed further, it is necessary to be more preciseabout the nature of the duplicated database and the operations allowedon it. A constant, read-only database is at one extreme. The task of theDBMPs is trivial in this case. They simply respond to value retrievalrequests. At the other extreme is a general shared database wherefunctional modification requests (such as "X := f(X,Y,Z)") are allowedand/or where it is necessary to completely restrict access to entrieswhile they are being modified. In this case all the problems of shareddatabases on a single computer system arise (e.g., the need forsynchronization mechanisms and the resulting potential deadlocksituations), as well as those unique to having multiple database copiesdistributed among independent computers. For example, a completelygeneral system must deal with the possibility of communication failureswhich cause the network to become partitioned into two or more sub-networks. Any solution which relies on locking an element of thedatabase for synchronized modification must cope with the possibility ofprocesses in non-communicating sub-networks attempting to lock the sameelement. Either they both must be allowed to do so (which violates thelock discipline), or they both must wait till the partition ceases(which may take arbitrarily long), or some form of centralized orhierarchical control must be used, with a resulting dependency of someDBMPs on others for all modifications and perhaps accesses as well.