Search Results

Search found 29753 results on 1191 pages for 'best practices'.

Page 355/1191 | < Previous Page | 351 352 353 354 355 356 357 358 359 360 361 362  | Next Page >

• Using dates, and times in SQL Server: a workbench approach

  In this workbench, Robyn Page provides a gentle introduction to the use of dates in SQL Server. In this new version of her article, it is brought up to date with the newer Datetime features in SQL Server 2005 and 2008. Calling all Exceptional DBAs...Enter the awards now for your chance to become 2010’s Exceptional DBA and don’t forget to download your free copy of Brad McGehee’s Day-to-Day DBA Best Practices poster. Nominate now.

  Read the article

• 3 Easy Ways to Submit a Sitemap

  Submitting a sitemap is one of the effective SEO practices even if it is coded in HTML or XML. If you have a new website and you want it to be indexed immediately by popular search engines, create and submit a sitemap. Here are the 3 easy ways to do it.

  Read the article

• How to Document and Configure SQL Server Instance Settings

  Occasionally, when you install identical databases on two different SQL Server instances, they will behave in surprisingly different ways. Why? Most likely, it is down to different configuration settings. There are around seventy of these settings and the DBA needs to be aware of the effect that many of them have. Brad McGehee explains them all in enough detail to help with most common configuration problems, and suggests some best practices.

  Read the article

• Natural Search Engine Optimization - Don't "Game the System" Or You Will Get Banned!

  When focusing on natural search engine optimization, it is important that you keep the process "white hat." You see, when it comes to SEO, there are basically three schools of thought: White hat, Gray hat, and Black hat. As you can probably infer, white hat is following the rules, gray hat is a little in between, and black hat is going against parameters that Google and other major search engines have set for ethical SEO practices.

  Read the article

• Building Search Into Your Organization

  Most corporations understand that a great search strategy relies mostly on incorporating the absolute best practices throughout their organizations. Here are some tips to great content architecture across your organization.

  Read the article

• Introduction to SEO For Beginners

  SEO is probably one of the most valuable skills you can learn in making money online through internet marketing. If done correctly, SEO can bring thousands of targeted visitors to your sales page, all for free. Many people have gotten rich off of well-executed SEO practices.

  Read the article

• What important aspects of Java should I know coming from Python?

  - by Macuser

  So, I've been browsing the job market, and it seems almost every programmer position requires either knowledge in the .NET, C#, or Java, and I'm looking to pick up Java, as I am not interesting very much with programming for Windows environments. So, what syntax differences should I look out for (except different class names), and any practices that I should avoid using in Java which is normally used in Python?

  Read the article

• How to improve UI development skills (for a Java developer)?

  - by bluetech

  I have worked on backend development with mostly Java. For past 6 months I have been working on UI a lot and I want to improve my skills. I am aware of HTML, CSS and JavaScript (also jQuery and YUI) but I have never been able to master them so that I can develop efficient and maintainable solutions much quicker than how I do now. Can other UI developers give me any tips/resources? I also wanted to learn about patterns and best practices for UI development.

  Read the article

• Which devices is my app working on

  - by Woojah

  My team is developing an app that will work on about 100 (or more) different android devices. We are having trouble testing it since we are not sure how to verify if it works on all the different devices. Can anybody suggest some best practices, a testing framework, or some sort of way to give us feedback on how to test our app and/or get feedback from our users so they can tell us the problems they are having?

  Read the article

• Is there a canonical book on parallel programming with focus on C++ ?

  - by quant_dev

  I am looking for a good book about parallel programming with focus on C++. Something suitable for a person reasonably good in C++ programming, but with no experience in concurrent software development. On the other hand, I'd prefer a practical book, without loads of silly examples about philosophers eating lunch. Is there a book out there that's the de-facto standard for describing best practices, design methodologies, and other helpful information on parallel programming with focus on C++ ? What about that book makes it special?

  Read the article

• 6 Traits of Websites That Generate Business Leads

  What makes some websites attract prospects and generate business leads while others languish? One thing is certain, it's no accident. Regardless of the product or service being offered, great lead generating sites typically share these best-practices:

  Read the article

• 5 Ways to Reduce the Google Sandbox Effect

  The most used and most popular search engine is Google all over the World Wide Web. Google is very much strict with the SEO practices every website is using. Google sandbox is known as the effect after a website is put into test if it followed the policy and guidelines of Google.

  Read the article

• 5 Ways to Reduce the Google Sandbox Effect

  The most used and most popular search engine is Google all over the World Wide Web. Google is very much strict with the SEO practices every website is using. Google sandbox is known as the effect after a website is put into test if it followed the policy and guidelines of Google.

  Read the article

• SQL Server Integration Services package to delete files from a Network or Local path based on date

  We have a requirement to delete a group of files that are older than the specified number of days from the company file share. Due to the complex folder hierarchy and delicate nature of the data stored in these files, this task has to be originated from SQL Server. However, due to company security policy, and based on SQL Server security best practices, we blocked access to OLE Automation stored procedures, CLR features, and xp_cmdshell. Is there any way to accomplish this task without using these features?

  Read the article

• The components of a brownfield application

  This article is taken from the book Brownfield Application Development in .NET. The authors define brownfield applications and discuss their three components - existing codebase, contamination by poor practices, and potential for reuse or improvement.

  Read the article

• Uncovering SEO Methods of Your Competitor

  Despite many proven and verifiable SEO techniques that work there is one valuable source of information that should not be overlooked. This source is your competition. If you try to use all good practices your competitor is using you will be able to significantly improve your SEO score.

  Read the article

• Introduction to SEO For Beginners

  SEO is probably one of the most valuable skills you can learn in making money online through internet marketing. If done correctly, SEO can bring thousands of targeted visitors to your sales page, all for free. Many people have gotten rich off of well-executed SEO practices.

  Read the article

• One-Time Passwords via Mobile Phone -- Sound Security Practice or Pain in the Neck?

  Will applying one-time password technology on mobile devices result in more sound security practices and with that more secure financial transactions? One authentication company thinks so.

  Read the article

• Is SEO Critical to Your Business? Consider This

  The number of people turning to the Internet to get answers to their questions is growing by leaps and bounds. Currently, the amount of people utilizing search engines like Google to find information, answers, shopping solutions, and more, sings to the tune of 64%! And as that number will undoubtedly grow, properly implementing Search Engine Optimization (SEO) practices into your marketing grows with it.

  Read the article

• SEO - A Part of Any Online Business!

  SEO is necessary for improving the ranking of any site. The practices must be implemented for every business site for better profits.

  Read the article

• Fusion Middleware MAA ????????

  - by katsumii

  ???????????MAA???????????????????? SOA 11g ??????????·?????? OracleDB 11g ?????? (INOUE Katsumi @ Tokyo)??????????????????DB11g??????SecureFiles ??????????????? ???????????MAA?????????????????????Large OBject(LOB)????? ?????????????????????????????????????????????????????????????MAA???????????????????? Oracle Blogs ???????: [FMW] MAA Best Practices - Oracle Fusion MiddlewareMAA = Maximum Availability Architecture????????????????????????????????????????????(????????)???

  Read the article

• ?RAC????????????

  - by Allen Gao

  Normal 0 7.8 ? 0 2 false false false EN-US ZH-CN X-NONE DefSemiHidden="true" DefQFormat="false" DefPriority="99" LatentStyleCount="267" UnhideWhenUsed="false" QFormat="true" Name="Normal"/ UnhideWhenUsed="false" QFormat="true" Name="heading 1"/ UnhideWhenUsed="false" QFormat="true" Name="Title"/ UnhideWhenUsed="false" QFormat="true" Name="Subtitle"/ UnhideWhenUsed="false" QFormat="true" Name="Strong"/ UnhideWhenUsed="false" QFormat="true" Name="Emphasis"/ UnhideWhenUsed="false" Name="Table Grid"/ UnhideWhenUsed="false" QFormat="true" Name="No Spacing"/ UnhideWhenUsed="false" Name="Light Shading"/ UnhideWhenUsed="false" Name="Light List"/ UnhideWhenUsed="false" Name="Light Grid"/ UnhideWhenUsed="false" Name="Medium Shading 1"/ UnhideWhenUsed="false" Name="Medium Shading 2"/ UnhideWhenUsed="false" Name="Medium List 1"/ UnhideWhenUsed="false" Name="Medium List 2"/ UnhideWhenUsed="false" Name="Medium Grid 1"/ UnhideWhenUsed="false" Name="Medium Grid 2"/ UnhideWhenUsed="false" Name="Medium Grid 3"/ UnhideWhenUsed="false" Name="Dark List"/ UnhideWhenUsed="false" Name="Colorful Shading"/ UnhideWhenUsed="false" Name="Colorful List"/ UnhideWhenUsed="false" Name="Colorful Grid"/ UnhideWhenUsed="false" Name="Light Shading Accent 1"/ UnhideWhenUsed="false" Name="Light List Accent 1"/ UnhideWhenUsed="false" Name="Light Grid Accent 1"/ UnhideWhenUsed="false" Name="Medium Shading 1 Accent 1"/ UnhideWhenUsed="false" Name="Medium Shading 2 Accent 1"/ UnhideWhenUsed="false" Name="Medium List 1 Accent 1"/ UnhideWhenUsed="false" QFormat="true" Name="List Paragraph"/ UnhideWhenUsed="false" QFormat="true" Name="Quote"/ UnhideWhenUsed="false" QFormat="true" Name="Intense Quote"/ UnhideWhenUsed="false" Name="Medium List 2 Accent 1"/ UnhideWhenUsed="false" Name="Medium Grid 1 Accent 1"/ UnhideWhenUsed="false" Name="Medium Grid 2 Accent 1"/ UnhideWhenUsed="false" Name="Medium Grid 3 Accent 1"/ UnhideWhenUsed="false" Name="Dark List Accent 1"/ UnhideWhenUsed="false" Name="Colorful Shading Accent 1"/ UnhideWhenUsed="false" Name="Colorful List Accent 1"/ UnhideWhenUsed="false" Name="Colorful Grid Accent 1"/ UnhideWhenUsed="false" Name="Light Shading Accent 2"/ UnhideWhenUsed="false" Name="Light List Accent 2"/ UnhideWhenUsed="false" Name="Light Grid Accent 2"/ UnhideWhenUsed="false" Name="Medium Shading 1 Accent 2"/ UnhideWhenUsed="false" Name="Medium Shading 2 Accent 2"/ UnhideWhenUsed="false" Name="Medium List 1 Accent 2"/ UnhideWhenUsed="false" Name="Medium List 2 Accent 2"/ UnhideWhenUsed="false" Name="Medium Grid 1 Accent 2"/ UnhideWhenUsed="false" Name="Medium Grid 2 Accent 2"/ UnhideWhenUsed="false" Name="Medium Grid 3 Accent 2"/ UnhideWhenUsed="false" Name="Dark List Accent 2"/ UnhideWhenUsed="false" Name="Colorful Shading Accent 2"/ UnhideWhenUsed="false" Name="Colorful List Accent 2"/ UnhideWhenUsed="false" Name="Colorful Grid Accent 2"/ UnhideWhenUsed="false" Name="Light Shading Accent 3"/ UnhideWhenUsed="false" Name="Light List Accent 3"/ UnhideWhenUsed="false" Name="Light Grid Accent 3"/ UnhideWhenUsed="false" Name="Medium Shading 1 Accent 3"/ UnhideWhenUsed="false" Name="Medium Shading 2 Accent 3"/ UnhideWhenUsed="false" Name="Medium List 1 Accent 3"/ UnhideWhenUsed="false" Name="Medium List 2 Accent 3"/ UnhideWhenUsed="false" Name="Medium Grid 1 Accent 3"/ UnhideWhenUsed="false" Name="Medium Grid 2 Accent 3"/ UnhideWhenUsed="false" Name="Medium Grid 3 Accent 3"/ UnhideWhenUsed="false" Name="Dark List Accent 3"/ UnhideWhenUsed="false" Name="Colorful Shading Accent 3"/ UnhideWhenUsed="false" Name="Colorful List Accent 3"/ UnhideWhenUsed="false" Name="Colorful Grid Accent 3"/ UnhideWhenUsed="false" Name="Light Shading Accent 4"/ UnhideWhenUsed="false" Name="Light List Accent 4"/ UnhideWhenUsed="false" Name="Light Grid Accent 4"/ UnhideWhenUsed="false" Name="Medium Shading 1 Accent 4"/ UnhideWhenUsed="false" Name="Medium Shading 2 Accent 4"/ UnhideWhenUsed="false" Name="Medium List 1 Accent 4"/ UnhideWhenUsed="false" Name="Medium List 2 Accent 4"/ UnhideWhenUsed="false" Name="Medium Grid 1 Accent 4"/ UnhideWhenUsed="false" Name="Medium Grid 2 Accent 4"/ UnhideWhenUsed="false" Name="Medium Grid 3 Accent 4"/ UnhideWhenUsed="false" Name="Dark List Accent 4"/ UnhideWhenUsed="false" Name="Colorful Shading Accent 4"/ UnhideWhenUsed="false" Name="Colorful List Accent 4"/ UnhideWhenUsed="false" Name="Colorful Grid Accent 4"/ UnhideWhenUsed="false" Name="Light Shading Accent 5"/ UnhideWhenUsed="false" Name="Light List Accent 5"/ UnhideWhenUsed="false" Name="Light Grid Accent 5"/ UnhideWhenUsed="false" Name="Medium Shading 1 Accent 5"/ UnhideWhenUsed="false" Name="Medium Shading 2 Accent 5"/ UnhideWhenUsed="false" Name="Medium List 1 Accent 5"/ UnhideWhenUsed="false" Name="Medium List 2 Accent 5"/ UnhideWhenUsed="false" Name="Medium Grid 1 Accent 5"/ UnhideWhenUsed="false" Name="Medium Grid 2 Accent 5"/ UnhideWhenUsed="false" Name="Medium Grid 3 Accent 5"/ UnhideWhenUsed="false" Name="Dark List Accent 5"/ UnhideWhenUsed="false" Name="Colorful Shading Accent 5"/ UnhideWhenUsed="false" Name="Colorful List Accent 5"/ UnhideWhenUsed="false" Name="Colorful Grid Accent 5"/ UnhideWhenUsed="false" Name="Light Shading Accent 6"/ UnhideWhenUsed="false" Name="Light List Accent 6"/ UnhideWhenUsed="false" Name="Light Grid Accent 6"/ UnhideWhenUsed="false" Name="Medium Shading 1 Accent 6"/ UnhideWhenUsed="false" Name="Medium Shading 2 Accent 6"/ UnhideWhenUsed="false" Name="Medium List 1 Accent 6"/ UnhideWhenUsed="false" Name="Medium List 2 Accent 6"/ UnhideWhenUsed="false" Name="Medium Grid 1 Accent 6"/ UnhideWhenUsed="false" Name="Medium Grid 2 Accent 6"/ UnhideWhenUsed="false" Name="Medium Grid 3 Accent 6"/ UnhideWhenUsed="false" Name="Dark List Accent 6"/ UnhideWhenUsed="false" Name="Colorful Shading Accent 6"/ UnhideWhenUsed="false" Name="Colorful List Accent 6"/ UnhideWhenUsed="false" Name="Colorful Grid Accent 6"/ UnhideWhenUsed="false" QFormat="true" Name="Subtle Emphasis"/ UnhideWhenUsed="false" QFormat="true" Name="Intense Emphasis"/ UnhideWhenUsed="false" QFormat="true" Name="Subtle Reference"/ UnhideWhenUsed="false" QFormat="true" Name="Intense Reference"/ UnhideWhenUsed="false" QFormat="true" Name="Book Title"/ /* Style Definitions */ table.MsoNormalTable {mso-style-name:????; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.5pt; mso-bidi-font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-font-kerning:1.0pt;} ????????????????????????????????????????,??????????????Oracle RAC?????????????????????????????,???????????????????,??????RAC???????????,????????????????????????????????????,????3???RAC????????????? ????????MOS ??"Top 11 Things to do NOW to Stabilize your RAC Cluster Environment”(DOC ID 1344678.1)???,???,??????3???????????,?????????????????????????????,???,?????????????????,??,??????????????,??????????????????????,?????????????,??????????????????????,???????RAC DBA???? ??????? (PSU)??,?????????PSU? ???????????,???????Oracle???????????(PSU)???PSU?????????????????,??PSU???????????????????PSU????????,???????????????PSU,????????6????????????????????BUG????,??????????,?????????????????????,???9???,???RAC???(Cluster)BUG,??7%??BUG??????,??????????BUG??????????????????????PSU??????RAC???,PSU????????: PSU?????Grid Infrastructure(GI)home,???????????RDBMS home???????,??GI home????PSU,?????home?????,??????????GI????????????,??????,??RDBMS PSU,GI PSU??????????GI home??????PSU,???????RDBMS??PSU? RAC????PSU????rolling????? –?????????GI? RDBMS?????????????????,??PSU???????,???????????????? ???????????PSU,????????????,?????????PSU????,???RAC?????????????PSU???,???????????????????? ??PSU?????, ??????MOS??: NOTE 854428.1   Intro to Patch Set Updates (PSU) NOTE 1082394.1 11.2.0.X Grid Infrastructure PSU Known Issues NOTE 756671.1   Oracle Recommended Patches -- Oracle Database NOTE 161549.1   Oracle Database, Networking and Grid Agent Patches for Microsoft Platforms NOTE 810394.1   RAC and Oracle Clusterware Best Practices and Starter Kit 11gR2???????,?Diagwait???13? ?2012?,??45%????????11gR2???????,????diagwait?13????RAC???????????,????diagwait??????????????,????????????????, diagwait??RAC?????????????: ?????,??????OPROCD?????1??0.5?????,????,??OPROCD??? 1.5????,?????????diagwait????13??OPROCD??????????10?( diagwait - CSS????[???3?]),????????OPROCD???????????????'?'?????????????,1.5??????????????????OPROCD?????????????11?(1?????+10????)? ?????/???????,??diagwait,??????????????????????,??,????????????? ?11g?2?(11.2.0.1?????)??,?????????????,???????,??????????????????,????????????????,?????????????????????diagwait????????,????????????????????,????????Oracle?????(OCR),?????????OCR???????????,?????????diagwai?????????????????: # $CLUSTERWARE_HOME\bin\crsctl get css diagwait ????DIAGWAIT???,??????MOS??: NOTE 567730.1  Changes in Oracle Clusterware on Linux with the 10.2.0.4 Patchset NOTE 559365.1  Using Diagwait as a diagnostic to get more information for diagnosing Oracle Clusterware Node evictions NOTE 810394.1 RAC and Oracle Clusterware Best Practices and Starter Kit ??OS Watcher Black Box(OSWbb) ? Cluster Health Monitor(CHM) ????????OS??????????????,??,??????OS Watcher Black Box(OSWbb)(??OS Watcher)?Cluster Health Monitor(CHM)????????OS???,??DBA????????????????????????????,?????????????,??????????,?????????????????????????OS????????,????????????,???????????????????? OSWbb?????????,??????,????OS??????????????,????OS??????OSWbb???????: ?????,??30??????????OS?????????????(??5??)????????????????????,?1???5????????????????????????30????????,Oracle???????????????OS?????????????,Oracle??????OSWbb?20???????? OSWbb?????????????????Oracle???????????????????OS????,??,?????????????????????????Oracle???????,?????????????,????????????????? ???11.2.0.3??,??????(HP-UX??)?,Oracle GI?????????,Cluster Health Monitor (CHM)?CHM??????,?????OSW????,??,???????OSW????,?????????? Oracle??????????????????OSWbb?/?CHM,?????????,????????????????????,??????????OSWbb,???????????RAC??,??????????????????(???NOTE 580513.1“How To Start OS Watcher Black Box Every System Boot”??????)? ??OSWbb?CHM?????, ??????MOS??: NOTE 301137.1   OS Watcher Black Box User Guide NOTE 1328466.1 Cluster Health Monitor (CHM) FAQ NOTE 810394.1   RAC and Oracle Clusterware Best Practices and Starter Kit ?? ?????????RAC/ Oracle?????????????3???????????3?,?????RAC??????,?????????????????,?????MOS??: NOTE 1344678.1 Top 11 Things to do NOW to Stabilize your RAC Cluster Environment ????,???MOS-RAC/Scalability community??,?Oracle???????????,????RAC/ Oracle?????

  Read the article

• Inheritance Mapping Strategies with Entity Framework Code First CTP5: Part 3 – Table per Concrete Type (TPC) and Choosing Strategy Guidelines

  - by mortezam

  This is the third (and last) post in a series that explains different approaches to map an inheritance hierarchy with EF Code First. I've described these strategies in previous posts: Part 1 – Table per Hierarchy (TPH) Part 2 – Table per Type (TPT)In today’s blog post I am going to discuss Table per Concrete Type (TPC) which completes the inheritance mapping strategies supported by EF Code First. At the end of this post I will provide some guidelines to choose an inheritance strategy mainly based on what we've learned in this series. TPC and Entity Framework in the Past Table per Concrete type is somehow the simplest approach suggested, yet using TPC with EF is one of those concepts that has not been covered very well so far and I've seen in some resources that it was even discouraged. The reason for that is just because Entity Data Model Designer in VS2010 doesn't support TPC (even though the EF runtime does). That basically means if you are following EF's Database-First or Model-First approaches then configuring TPC requires manually writing XML in the EDMX file which is not considered to be a fun practice. Well, no more. You'll see that with Code First, creating TPC is perfectly possible with fluent API just like other strategies and you don't need to avoid TPC due to the lack of designer support as you would probably do in other EF approaches. Table per Concrete Type (TPC)In Table per Concrete type (aka Table per Concrete class) we use exactly one table for each (nonabstract) class. All properties of a class, including inherited properties, can be mapped to columns of this table, as shown in the following figure: As you can see, the SQL schema is not aware of the inheritance; effectively, we’ve mapped two unrelated tables to a more expressive class structure. If the base class was concrete, then an additional table would be needed to hold instances of that class. I have to emphasize that there is no relationship between the database tables, except for the fact that they share some similar columns. TPC Implementation in Code First Just like the TPT implementation, we need to specify a separate table for each of the subclasses. We also need to tell Code First that we want all of the inherited properties to be mapped as part of this table. In CTP5, there is a new helper method on EntityMappingConfiguration class called MapInheritedProperties that exactly does this for us. Here is the complete object model as well as the fluent API to create a TPC mapping: public abstract class BillingDetail {     public int BillingDetailId { get; set; }     public string Owner { get; set; }     public string Number { get; set; } }          public class BankAccount : BillingDetail {     public string BankName { get; set; }     public string Swift { get; set; } }          public class CreditCard : BillingDetail {     public int CardType { get; set; }     public string ExpiryMonth { get; set; }     public string ExpiryYear { get; set; } }      public class InheritanceMappingContext : DbContext {     public DbSet<BillingDetail> BillingDetails { get; set; }              protected override void OnModelCreating(ModelBuilder modelBuilder)     {         modelBuilder.Entity<BankAccount>().Map(m =>         {             m.MapInheritedProperties();             m.ToTable("BankAccounts");         });         modelBuilder.Entity<CreditCard>().Map(m =>         {             m.MapInheritedProperties();             m.ToTable("CreditCards");         });                 } } The Importance of EntityMappingConfiguration ClassAs a side note, it worth mentioning that EntityMappingConfiguration class turns out to be a key type for inheritance mapping in Code First. Here is an snapshot of this class: namespace System.Data.Entity.ModelConfiguration.Configuration.Mapping {     public class EntityMappingConfiguration<TEntityType> where TEntityType : class     {         public ValueConditionConfiguration Requires(string discriminator);         public void ToTable(string tableName);         public void MapInheritedProperties();     } } As you have seen so far, we used its Requires method to customize TPH. We also used its ToTable method to create a TPT and now we are using its MapInheritedProperties along with ToTable method to create our TPC mapping. TPC Configuration is Not Done Yet!We are not quite done with our TPC configuration and there is more into this story even though the fluent API we saw perfectly created a TPC mapping for us in the database. To see why, let's start working with our object model. For example, the following code creates two new objects of BankAccount and CreditCard types and tries to add them to the database: using (var context = new InheritanceMappingContext()) {     BankAccount bankAccount = new BankAccount();     CreditCard creditCard = new CreditCard() { CardType = 1 };                      context.BillingDetails.Add(bankAccount);     context.BillingDetails.Add(creditCard);     context.SaveChanges(); } Running this code throws an InvalidOperationException with this message: The changes to the database were committed successfully, but an error occurred while updating the object context. The ObjectContext might be in an inconsistent state. Inner exception message: AcceptChanges cannot continue because the object's key values conflict with another object in the ObjectStateManager. Make sure that the key values are unique before calling AcceptChanges. The reason we got this exception is because DbContext.SaveChanges() internally invokes SaveChanges method of its internal ObjectContext. ObjectContext's SaveChanges method on its turn by default calls AcceptAllChanges after it has performed the database modifications. AcceptAllChanges method merely iterates over all entries in ObjectStateManager and invokes AcceptChanges on each of them. Since the entities are in Added state, AcceptChanges method replaces their temporary EntityKey with a regular EntityKey based on the primary key values (i.e. BillingDetailId) that come back from the database and that's where the problem occurs since both the entities have been assigned the same value for their primary key by the database (i.e. on both BillingDetailId = 1) and the problem is that ObjectStateManager cannot track objects of the same type (i.e. BillingDetail) with the same EntityKey value hence it throws. If you take a closer look at the TPC's SQL schema above, you'll see why the database generated the same values for the primary keys: the BillingDetailId column in both BankAccounts and CreditCards table has been marked as identity. How to Solve The Identity Problem in TPC As you saw, using SQL Server’s int identity columns doesn't work very well together with TPC since there will be duplicate entity keys when inserting in subclasses tables with all having the same identity seed. Therefore, to solve this, either a spread seed (where each table has its own initial seed value) will be needed, or a mechanism other than SQL Server’s int identity should be used. Some other RDBMSes have other mechanisms allowing a sequence (identity) to be shared by multiple tables, and something similar can be achieved with GUID keys in SQL Server. While using GUID keys, or int identity keys with different starting seeds will solve the problem but yet another solution would be to completely switch off identity on the primary key property. As a result, we need to take the responsibility of providing unique keys when inserting records to the database. We will go with this solution since it works regardless of which database engine is used. Switching Off Identity in Code First We can switch off identity simply by placing DatabaseGenerated attribute on the primary key property and pass DatabaseGenerationOption.None to its constructor. DatabaseGenerated attribute is a new data annotation which has been added to System.ComponentModel.DataAnnotations namespace in CTP5: public abstract class BillingDetail {     [DatabaseGenerated(DatabaseGenerationOption.None)]     public int BillingDetailId { get; set; }     public string Owner { get; set; }     public string Number { get; set; } } As always, we can achieve the same result by using fluent API, if you prefer that: modelBuilder.Entity<BillingDetail>()             .Property(p => p.BillingDetailId)             .HasDatabaseGenerationOption(DatabaseGenerationOption.None); Working With The Object Model Our TPC mapping is ready and we can try adding new records to the database. But, like I said, now we need to take care of providing unique keys when creating new objects: using (var context = new InheritanceMappingContext()) {     BankAccount bankAccount = new BankAccount()      {          BillingDetailId = 1                          };     CreditCard creditCard = new CreditCard()      {          BillingDetailId = 2,         CardType = 1     };                      context.BillingDetails.Add(bankAccount);     context.BillingDetails.Add(creditCard);     context.SaveChanges(); } Polymorphic Associations with TPC is Problematic The main problem with this approach is that it doesn’t support Polymorphic Associations very well. After all, in the database, associations are represented as foreign key relationships and in TPC, the subclasses are all mapped to different tables so a polymorphic association to their base class (abstract BillingDetail in our example) cannot be represented as a simple foreign key relationship. For example, consider the the domain model we introduced here where User has a polymorphic association with BillingDetail. This would be problematic in our TPC Schema, because if User has a many-to-one relationship with BillingDetail, the Users table would need a single foreign key column, which would have to refer both concrete subclass tables. This isn’t possible with regular foreign key constraints. Schema Evolution with TPC is Complex A further conceptual problem with this mapping strategy is that several different columns, of different tables, share exactly the same semantics. This makes schema evolution more complex. For example, a change to a base class property results in changes to multiple columns. It also makes it much more difficult to implement database integrity constraints that apply to all subclasses. Generated SQLLet's examine SQL output for polymorphic queries in TPC mapping. For example, consider this polymorphic query for all BillingDetails and the resulting SQL statements that being executed in the database: var query = from b in context.BillingDetails select b; Just like the SQL query generated by TPT mapping, the CASE statements that you see in the beginning of the query is merely to ensure columns that are irrelevant for a particular row have NULL values in the returning flattened table. (e.g. BankName for a row that represents a CreditCard type). TPC's SQL Queries are Union Based As you can see in the above screenshot, the first SELECT uses a FROM-clause subquery (which is selected with a red rectangle) to retrieve all instances of BillingDetails from all concrete class tables. The tables are combined with a UNION operator, and a literal (in this case, 0 and 1) is inserted into the intermediate result; (look at the lines highlighted in yellow.) EF reads this to instantiate the correct class given the data from a particular row. A union requires that the queries that are combined, project over the same columns; hence, EF has to pad and fill up nonexistent columns with NULL. This query will really perform well since here we can let the database optimizer find the best execution plan to combine rows from several tables. There is also no Joins involved so it has a better performance than the SQL queries generated by TPT where a Join is required between the base and subclasses tables. Choosing Strategy GuidelinesBefore we get into this discussion, I want to emphasize that there is no one single "best strategy fits all scenarios" exists. As you saw, each of the approaches have their own advantages and drawbacks. Here are some rules of thumb to identify the best strategy in a particular scenario: If you don’t require polymorphic associations or queries, lean toward TPC—in other words, if you never or rarely query for BillingDetails and you have no class that has an association to BillingDetail base class. I recommend TPC (only) for the top level of your class hierarchy, where polymorphism isn’t usually required, and when modification of the base class in the future is unlikely. If you do require polymorphic associations or queries, and subclasses declare relatively few properties (particularly if the main difference between subclasses is in their behavior), lean toward TPH. Your goal is to minimize the number of nullable columns and to convince yourself (and your DBA) that a denormalized schema won’t create problems in the long run. If you do require polymorphic associations or queries, and subclasses declare many properties (subclasses differ mainly by the data they hold), lean toward TPT. Or, depending on the width and depth of your inheritance hierarchy and the possible cost of joins versus unions, use TPC. By default, choose TPH only for simple problems. For more complex cases (or when you’re overruled by a data modeler insisting on the importance of nullability constraints and normalization), you should consider the TPT strategy. But at that point, ask yourself whether it may not be better to remodel inheritance as delegation in the object model (delegation is a way of making composition as powerful for reuse as inheritance). Complex inheritance is often best avoided for all sorts of reasons unrelated to persistence or ORM. EF acts as a buffer between the domain and relational models, but that doesn’t mean you can ignore persistence concerns when designing your classes. SummaryIn this series, we focused on one of the main structural aspect of the object/relational paradigm mismatch which is inheritance and discussed how EF solve this problem as an ORM solution. We learned about the three well-known inheritance mapping strategies and their implementations in EF Code First. Hopefully it gives you a better insight about the mapping of inheritance hierarchies as well as choosing the best strategy for your particular scenario. Happy New Year and Happy Code-Firsting! References ADO.NET team blog Java Persistence with Hibernate book a { color: #5A99FF; } a:visited { color: #5A99FF; } .title { padding-bottom: 5px; font-family: Segoe UI; font-size: 11pt; font-weight: bold; padding-top: 15px; } .code, .typeName { font-family: consolas; } .typeName { color: #2b91af; } .padTop5 { padding-top: 5px; } .padTop10 { padding-top: 10px; } .exception { background-color: #f0f0f0; font-style: italic; padding-bottom: 5px; padding-left: 5px; padding-top: 5px; padding-right: 5px; }

  Read the article

• Antivirus Configuration for dedicated SQL and dedicated IIS Servers

  - by Wayne Arthurton

  Our corporate standard is McAfee Enterprise, unfortunately this is non-negotiable. On two types of servers I'm responsible for, SQL & Web, we have noticed major performance issues with the corporate standard setup. Max scan time 45sec One policy for all processes Scan ALL files on write, read and open for backup Heuristics: Find unknown programs, trojans and macros Detect unwanted programs Exclude: EVT, LDF, LOG, MDF, VMD, , windows file protection) This of course still causes major slowdowns. IIS .NET recompiles are slow especially with SharePoint, SQL backups and restores, SQL Analysis Services, Integration Services and temp data from them as well. I have looked from time to time, for some best practices on setting up McAfee of SQL & SQL Analysis Service, SQL Integration Service, Visual Studio, Sharepoint, and .NET web servers in general. How do people setup McAfee enterprise on their corporate serves keeping security intact, but affecting performance as minimally as possible? Has anyone run across white papers on these setups? Obviously some are case by case, but there must be some best practices out there somewhere.

  Read the article

• Domain Environment + Certificate Authority + Server 2008 R2

  - by user1110302

  I have recently been delegated the task to setup a CA in our domain environment and have a question on why Microsoft does somethings the way they do lol. I have been trying to read up on what the best practices are for going about this task, and have decided that in an ideal CA environment you should have one “offline” Root CA, and then two subordinate CAs for redundancy/issuing the certs. That is all good, I understand how this works and why, but in messing with a sandbox I have setup, the way you go about adding certificate authorities to a domain environment seems extremely trivial and against all of their best practices… Dooes anyone know what the purpose is of an Enterprise Root CA that is integrated into Active Directory? From what I have read, once you setup an Enterprise Root CA that is integrated into Active Directory, it stays with Active Directory for the long haul and must not be turned off/renamed/touched under any circumstances. If this is true, that seems to go against the practice of setting up a standalone root CA, adding the subordinates, and then taking the root offline. Thanks for any feedback you may have to offer!

  Read the article

< Previous Page | 351 352 353 354 355 356 357 358 359 360 361 362  | Next Page >