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  • make select @@IDENTITY; a long?

    - by acidzombie24
    I am grabbing the last rowid and i am doing this select @@IDENTITY pk = (long)cmd.ExecuteScalar(); I get an invalid typecast bc this is int instead of long. Why doesnt this return a long? can i make it return long? Solution for now is to use pk = Convert.ToInt64(cmd.ExecuteScalar());

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  • In a MySQL SELECT query, can I use my "AS column" in a WHERE specification?

    - by user556352
    In my database I calculate distance between nodes with: SELECT DISTINCT dest.name, AsText(orig.location), AsText(dest.location), round((glength(linestringfromwkb(linestring((orig.location), (dest.location)))))) as distance FROM nodes orig, nodes dest WHERE orig.name='GERP' I would like to add "and distance < dest.visibility" at the end, but am told that distance is an unknown column. Any insight very much appreciated.

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  • What are good design practices when working with Entity Framework

    - by AD
    This will apply mostly for an asp.net application where the data is not accessed via soa. Meaning that you get access to the objects loaded from the framework, not Transfer Objects, although some recommendation still apply. This is a community post, so please add to it as you see fit. Applies to: Entity Framework 1.0 shipped with Visual Studio 2008 sp1. Why pick EF in the first place? Considering it is a young technology with plenty of problems (see below), it may be a hard sell to get on the EF bandwagon for your project. However, it is the technology Microsoft is pushing (at the expense of Linq2Sql, which is a subset of EF). In addition, you may not be satisfied with NHibernate or other solutions out there. Whatever the reasons, there are people out there (including me) working with EF and life is not bad.make you think. EF and inheritance The first big subject is inheritance. EF does support mapping for inherited classes that are persisted in 2 ways: table per class and table the hierarchy. The modeling is easy and there are no programming issues with that part. (The following applies to table per class model as I don't have experience with table per hierarchy, which is, anyway, limited.) The real problem comes when you are trying to run queries that include one or many objects that are part of an inheritance tree: the generated sql is incredibly awful, takes a long time to get parsed by the EF and takes a long time to execute as well. This is a real show stopper. Enough that EF should probably not be used with inheritance or as little as possible. Here is an example of how bad it was. My EF model had ~30 classes, ~10 of which were part of an inheritance tree. On running a query to get one item from the Base class, something as simple as Base.Get(id), the generated SQL was over 50,000 characters. Then when you are trying to return some Associations, it degenerates even more, going as far as throwing SQL exceptions about not being able to query more than 256 tables at once. Ok, this is bad, EF concept is to allow you to create your object structure without (or with as little as possible) consideration on the actual database implementation of your table. It completely fails at this. So, recommendations? Avoid inheritance if you can, the performance will be so much better. Use it sparingly where you have to. In my opinion, this makes EF a glorified sql-generation tool for querying, but there are still advantages to using it. And ways to implement mechanism that are similar to inheritance. Bypassing inheritance with Interfaces First thing to know with trying to get some kind of inheritance going with EF is that you cannot assign a non-EF-modeled class a base class. Don't even try it, it will get overwritten by the modeler. So what to do? You can use interfaces to enforce that classes implement some functionality. For example here is a IEntity interface that allow you to define Associations between EF entities where you don't know at design time what the type of the entity would be. public enum EntityTypes{ Unknown = -1, Dog = 0, Cat } public interface IEntity { int EntityID { get; } string Name { get; } Type EntityType { get; } } public partial class Dog : IEntity { // implement EntityID and Name which could actually be fields // from your EF model Type EntityType{ get{ return EntityTypes.Dog; } } } Using this IEntity, you can then work with undefined associations in other classes // lets take a class that you defined in your model. // that class has a mapping to the columns: PetID, PetType public partial class Person { public IEntity GetPet() { return IEntityController.Get(PetID,PetType); } } which makes use of some extension functions: public class IEntityController { static public IEntity Get(int id, EntityTypes type) { switch (type) { case EntityTypes.Dog: return Dog.Get(id); case EntityTypes.Cat: return Cat.Get(id); default: throw new Exception("Invalid EntityType"); } } } Not as neat as having plain inheritance, particularly considering you have to store the PetType in an extra database field, but considering the performance gains, I would not look back. It also cannot model one-to-many, many-to-many relationship, but with creative uses of 'Union' it could be made to work. Finally, it creates the side effet of loading data in a property/function of the object, which you need to be careful about. Using a clear naming convention like GetXYZ() helps in that regards. Compiled Queries Entity Framework performance is not as good as direct database access with ADO (obviously) or Linq2SQL. There are ways to improve it however, one of which is compiling your queries. The performance of a compiled query is similar to Linq2Sql. What is a compiled query? It is simply a query for which you tell the framework to keep the parsed tree in memory so it doesn't need to be regenerated the next time you run it. So the next run, you will save the time it takes to parse the tree. Do not discount that as it is a very costly operation that gets even worse with more complex queries. There are 2 ways to compile a query: creating an ObjectQuery with EntitySQL and using CompiledQuery.Compile() function. (Note that by using an EntityDataSource in your page, you will in fact be using ObjectQuery with EntitySQL, so that gets compiled and cached). An aside here in case you don't know what EntitySQL is. It is a string-based way of writing queries against the EF. Here is an example: "select value dog from Entities.DogSet as dog where dog.ID = @ID". The syntax is pretty similar to SQL syntax. You can also do pretty complex object manipulation, which is well explained [here][1]. Ok, so here is how to do it using ObjectQuery< string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); The first time you run this query, the framework will generate the expression tree and keep it in memory. So the next time it gets executed, you will save on that costly step. In that example EnablePlanCaching = true, which is unnecessary since that is the default option. The other way to compile a query for later use is the CompiledQuery.Compile method. This uses a delegate: static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => ctx.DogSet.FirstOrDefault(it => it.ID == id)); or using linq static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => (from dog in ctx.DogSet where dog.ID == id select dog).FirstOrDefault()); to call the query: query_GetDog.Invoke( YourContext, id ); The advantage of CompiledQuery is that the syntax of your query is checked at compile time, where as EntitySQL is not. However, there are other consideration... Includes Lets say you want to have the data for the dog owner to be returned by the query to avoid making 2 calls to the database. Easy to do, right? EntitySQL string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)).Include("Owner"); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); CompiledQuery static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => (from dog in ctx.DogSet.Include("Owner") where dog.ID == id select dog).FirstOrDefault()); Now, what if you want to have the Include parametrized? What I mean is that you want to have a single Get() function that is called from different pages that care about different relationships for the dog. One cares about the Owner, another about his FavoriteFood, another about his FavotireToy and so on. Basicly, you want to tell the query which associations to load. It is easy to do with EntitySQL public Dog Get(int id, string include) { string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)) .IncludeMany(include); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); } The include simply uses the passed string. Easy enough. Note that it is possible to improve on the Include(string) function (that accepts only a single path) with an IncludeMany(string) that will let you pass a string of comma-separated associations to load. Look further in the extension section for this function. If we try to do it with CompiledQuery however, we run into numerous problems: The obvious static readonly Func<Entities, int, string, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, string, Dog>((ctx, id, include) => (from dog in ctx.DogSet.Include(include) where dog.ID == id select dog).FirstOrDefault()); will choke when called with: query_GetDog.Invoke( YourContext, id, "Owner,FavoriteFood" ); Because, as mentionned above, Include() only wants to see a single path in the string and here we are giving it 2: "Owner" and "FavoriteFood" (which is not to be confused with "Owner.FavoriteFood"!). Then, let's use IncludeMany(), which is an extension function static readonly Func<Entities, int, string, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, string, Dog>((ctx, id, include) => (from dog in ctx.DogSet.IncludeMany(include) where dog.ID == id select dog).FirstOrDefault()); Wrong again, this time it is because the EF cannot parse IncludeMany because it is not part of the functions that is recognizes: it is an extension. Ok, so you want to pass an arbitrary number of paths to your function and Includes() only takes a single one. What to do? You could decide that you will never ever need more than, say 20 Includes, and pass each separated strings in a struct to CompiledQuery. But now the query looks like this: from dog in ctx.DogSet.Include(include1).Include(include2).Include(include3) .Include(include4).Include(include5).Include(include6) .[...].Include(include19).Include(include20) where dog.ID == id select dog which is awful as well. Ok, then, but wait a minute. Can't we return an ObjectQuery< with CompiledQuery? Then set the includes on that? Well, that what I would have thought so as well: static readonly Func<Entities, int, ObjectQuery<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, ObjectQuery<Dog>>((ctx, id) => (ObjectQuery<Dog>)(from dog in ctx.DogSet where dog.ID == id select dog)); public Dog GetDog( int id, string include ) { ObjectQuery<Dog> oQuery = query_GetDog(id); oQuery = oQuery.IncludeMany(include); return oQuery.FirstOrDefault; } That should have worked, except that when you call IncludeMany (or Include, Where, OrderBy...) you invalidate the cached compiled query because it is an entirely new one now! So, the expression tree needs to be reparsed and you get that performance hit again. So what is the solution? You simply cannot use CompiledQueries with parametrized Includes. Use EntitySQL instead. This doesn't mean that there aren't uses for CompiledQueries. It is great for localized queries that will always be called in the same context. Ideally CompiledQuery should always be used because the syntax is checked at compile time, but due to limitation, that's not possible. An example of use would be: you may want to have a page that queries which two dogs have the same favorite food, which is a bit narrow for a BusinessLayer function, so you put it in your page and know exactly what type of includes are required. Passing more than 3 parameters to a CompiledQuery Func is limited to 5 parameters, of which the last one is the return type and the first one is your Entities object from the model. So that leaves you with 3 parameters. A pitance, but it can be improved on very easily. public struct MyParams { public string param1; public int param2; public DateTime param3; } static readonly Func<Entities, MyParams, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, MyParams, IEnumerable<Dog>>((ctx, myParams) => from dog in ctx.DogSet where dog.Age == myParams.param2 && dog.Name == myParams.param1 and dog.BirthDate > myParams.param3 select dog); public List<Dog> GetSomeDogs( int age, string Name, DateTime birthDate ) { MyParams myParams = new MyParams(); myParams.param1 = name; myParams.param2 = age; myParams.param3 = birthDate; return query_GetDog(YourContext,myParams).ToList(); } Return Types (this does not apply to EntitySQL queries as they aren't compiled at the same time during execution as the CompiledQuery method) Working with Linq, you usually don't force the execution of the query until the very last moment, in case some other functions downstream wants to change the query in some way: static readonly Func<Entities, int, string, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, IEnumerable<Dog>>((ctx, age, name) => from dog in ctx.DogSet where dog.Age == age && dog.Name == name select dog); public IEnumerable<Dog> GetSomeDogs( int age, string name ) { return query_GetDog(YourContext,age,name); } public void DataBindStuff() { IEnumerable<Dog> dogs = GetSomeDogs(4,"Bud"); // but I want the dogs ordered by BirthDate gridView.DataSource = dogs.OrderBy( it => it.BirthDate ); } What is going to happen here? By still playing with the original ObjectQuery (that is the actual return type of the Linq statement, which implements IEnumerable), it will invalidate the compiled query and be force to re-parse. So, the rule of thumb is to return a List< of objects instead. static readonly Func<Entities, int, string, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, IEnumerable<Dog>>((ctx, age, name) => from dog in ctx.DogSet where dog.Age == age && dog.Name == name select dog); public List<Dog> GetSomeDogs( int age, string name ) { return query_GetDog(YourContext,age,name).ToList(); //<== change here } public void DataBindStuff() { List<Dog> dogs = GetSomeDogs(4,"Bud"); // but I want the dogs ordered by BirthDate gridView.DataSource = dogs.OrderBy( it => it.BirthDate ); } When you call ToList(), the query gets executed as per the compiled query and then, later, the OrderBy is executed against the objects in memory. It may be a little bit slower, but I'm not even sure. One sure thing is that you have no worries about mis-handling the ObjectQuery and invalidating the compiled query plan. Once again, that is not a blanket statement. ToList() is a defensive programming trick, but if you have a valid reason not to use ToList(), go ahead. There are many cases in which you would want to refine the query before executing it. Performance What is the performance impact of compiling a query? It can actually be fairly large. A rule of thumb is that compiling and caching the query for reuse takes at least double the time of simply executing it without caching. For complex queries (read inherirante), I have seen upwards to 10 seconds. So, the first time a pre-compiled query gets called, you get a performance hit. After that first hit, performance is noticeably better than the same non-pre-compiled query. Practically the same as Linq2Sql When you load a page with pre-compiled queries the first time you will get a hit. It will load in maybe 5-15 seconds (obviously more than one pre-compiled queries will end up being called), while subsequent loads will take less than 300ms. Dramatic difference, and it is up to you to decide if it is ok for your first user to take a hit or you want a script to call your pages to force a compilation of the queries. Can this query be cached? { Dog dog = from dog in YourContext.DogSet where dog.ID == id select dog; } No, ad-hoc Linq queries are not cached and you will incur the cost of generating the tree every single time you call it. Parametrized Queries Most search capabilities involve heavily parametrized queries. There are even libraries available that will let you build a parametrized query out of lamba expressions. The problem is that you cannot use pre-compiled queries with those. One way around that is to map out all the possible criteria in the query and flag which one you want to use: public struct MyParams { public string name; public bool checkName; public int age; public bool checkAge; } static readonly Func<Entities, MyParams, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, MyParams, IEnumerable<Dog>>((ctx, myParams) => from dog in ctx.DogSet where (myParams.checkAge == true && dog.Age == myParams.age) && (myParams.checkName == true && dog.Name == myParams.name ) select dog); protected List<Dog> GetSomeDogs() { MyParams myParams = new MyParams(); myParams.name = "Bud"; myParams.checkName = true; myParams.age = 0; myParams.checkAge = false; return query_GetDog(YourContext,myParams).ToList(); } The advantage here is that you get all the benifits of a pre-compiled quert. The disadvantages are that you most likely will end up with a where clause that is pretty difficult to maintain, that you will incur a bigger penalty for pre-compiling the query and that each query you run is not as efficient as it could be (particularly with joins thrown in). Another way is to build an EntitySQL query piece by piece, like we all did with SQL. protected List<Dod> GetSomeDogs( string name, int age) { string query = "select value dog from Entities.DogSet where 1 = 1 "; if( !String.IsNullOrEmpty(name) ) query = query + " and dog.Name == @Name "; if( age > 0 ) query = query + " and dog.Age == @Age "; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>( query, YourContext ); if( !String.IsNullOrEmpty(name) ) oQuery.Parameters.Add( new ObjectParameter( "Name", name ) ); if( age > 0 ) oQuery.Parameters.Add( new ObjectParameter( "Age", age ) ); return oQuery.ToList(); } Here the problems are: - there is no syntax checking during compilation - each different combination of parameters generate a different query which will need to be pre-compiled when it is first run. In this case, there are only 4 different possible queries (no params, age-only, name-only and both params), but you can see that there can be way more with a normal world search. - Noone likes to concatenate strings! Another option is to query a large subset of the data and then narrow it down in memory. This is particularly useful if you are working with a definite subset of the data, like all the dogs in a city. You know there are a lot but you also know there aren't that many... so your CityDog search page can load all the dogs for the city in memory, which is a single pre-compiled query and then refine the results protected List<Dod> GetSomeDogs( string name, int age, string city) { string query = "select value dog from Entities.DogSet where dog.Owner.Address.City == @City "; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>( query, YourContext ); oQuery.Parameters.Add( new ObjectParameter( "City", city ) ); List<Dog> dogs = oQuery.ToList(); if( !String.IsNullOrEmpty(name) ) dogs = dogs.Where( it => it.Name == name ); if( age > 0 ) dogs = dogs.Where( it => it.Age == age ); return dogs; } It is particularly useful when you start displaying all the data then allow for filtering. Problems: - Could lead to serious data transfer if you are not careful about your subset. - You can only filter on the data that you returned. It means that if you don't return the Dog.Owner association, you will not be able to filter on the Dog.Owner.Name So what is the best solution? There isn't any. You need to pick the solution that works best for you and your problem: - Use lambda-based query building when you don't care about pre-compiling your queries. - Use fully-defined pre-compiled Linq query when your object structure is not too complex. - Use EntitySQL/string concatenation when the structure could be complex and when the possible number of different resulting queries are small (which means fewer pre-compilation hits). - Use in-memory filtering when you are working with a smallish subset of the data or when you had to fetch all of the data on the data at first anyway (if the performance is fine with all the data, then filtering in memory will not cause any time to be spent in the db). Singleton access The best way to deal with your context and entities accross all your pages is to use the singleton pattern: public sealed class YourContext { private const string instanceKey = "On3GoModelKey"; YourContext(){} public static YourEntities Instance { get { HttpContext context = HttpContext.Current; if( context == null ) return Nested.instance; if (context.Items[instanceKey] == null) { On3GoEntities entity = new On3GoEntities(); context.Items[instanceKey] = entity; } return (YourEntities)context.Items[instanceKey]; } } class Nested { // Explicit static constructor to tell C# compiler // not to mark type as beforefieldinit static Nested() { } internal static readonly YourEntities instance = new YourEntities(); } } NoTracking, is it worth it? When executing a query, you can tell the framework to track the objects it will return or not. What does it mean? With tracking enabled (the default option), the framework will track what is going on with the object (has it been modified? Created? Deleted?) and will also link objects together, when further queries are made from the database, which is what is of interest here. For example, lets assume that Dog with ID == 2 has an owner which ID == 10. Dog dog = (from dog in YourContext.DogSet where dog.ID == 2 select dog).FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; Person owner = (from o in YourContext.PersonSet where o.ID == 10 select dog).FirstOrDefault(); //dog.OwnerReference.IsLoaded == true; If we were to do the same with no tracking, the result would be different. ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>) (from dog in YourContext.DogSet where dog.ID == 2 select dog); oDogQuery.MergeOption = MergeOption.NoTracking; Dog dog = oDogQuery.FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; ObjectQuery<Person> oPersonQuery = (ObjectQuery<Person>) (from o in YourContext.PersonSet where o.ID == 10 select o); oPersonQuery.MergeOption = MergeOption.NoTracking; Owner owner = oPersonQuery.FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; Tracking is very useful and in a perfect world without performance issue, it would always be on. But in this world, there is a price for it, in terms of performance. So, should you use NoTracking to speed things up? It depends on what you are planning to use the data for. Is there any chance that the data your query with NoTracking can be used to make update/insert/delete in the database? If so, don't use NoTracking because associations are not tracked and will causes exceptions to be thrown. In a page where there are absolutly no updates to the database, you can use NoTracking. Mixing tracking and NoTracking is possible, but it requires you to be extra careful with updates/inserts/deletes. The problem is that if you mix then you risk having the framework trying to Attach() a NoTracking object to the context where another copy of the same object exist with tracking on. Basicly, what I am saying is that Dog dog1 = (from dog in YourContext.DogSet where dog.ID == 2).FirstOrDefault(); ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>) (from dog in YourContext.DogSet where dog.ID == 2 select dog); oDogQuery.MergeOption = MergeOption.NoTracking; Dog dog2 = oDogQuery.FirstOrDefault(); dog1 and dog2 are 2 different objects, one tracked and one not. Using the detached object in an update/insert will force an Attach() that will say "Wait a minute, I do already have an object here with the same database key. Fail". And when you Attach() one object, all of its hierarchy gets attached as well, causing problems everywhere. Be extra careful. How much faster is it with NoTracking It depends on the queries. Some are much more succeptible to tracking than other. I don't have a fast an easy rule for it, but it helps. So I should use NoTracking everywhere then? Not exactly. There are some advantages to tracking object. The first one is that the object is cached, so subsequent call for that object will not hit the database. That cache is only valid for the lifetime of the YourEntities object, which, if you use the singleton code above, is the same as the page lifetime. One page request == one YourEntity object. So for multiple calls for the same object, it will load only once per page request. (Other caching mechanism could extend that). What happens when you are using NoTracking and try to load the same object multiple times? The database will be queried each time, so there is an impact there. How often do/should you call for the same object during a single page request? As little as possible of course, but it does happens. Also remember the piece above about having the associations connected automatically for your? You don't have that with NoTracking, so if you load your data in multiple batches, you will not have a link to between them: ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>)(from dog in YourContext.DogSet select dog); oDogQuery.MergeOption = MergeOption.NoTracking; List<Dog> dogs = oDogQuery.ToList(); ObjectQuery<Person> oPersonQuery = (ObjectQuery<Person>)(from o in YourContext.PersonSet select o); oPersonQuery.MergeOption = MergeOption.NoTracking; List<Person> owners = oPersonQuery.ToList(); In this case, no dog will have its .Owner property set. Some things to keep in mind when you are trying to optimize the performance. No lazy loading, what am I to do? This can be seen as a blessing in disguise. Of course it is annoying to load everything manually. However, it decreases the number of calls to the db and forces you to think about when you should load data. The more you can load in one database call the better. That was always true, but it is enforced now with this 'feature' of EF. Of course, you can call if( !ObjectReference.IsLoaded ) ObjectReference.Load(); if you want to, but a better practice is to force the framework to load the objects you know you will need in one shot. This is where the discussion about parametrized Includes begins to make sense. Lets say you have you Dog object public class Dog { public Dog Get(int id) { return YourContext.DogSet.FirstOrDefault(it => it.ID == id ); } } This is the type of function you work with all the time. It gets called from all over the place and once you have that Dog object, you will do very different things to it in different functions. First, it should be pre-compiled, because you will call that very often. Second, each different pages will want to have access to a different subset of the Dog data. Some will want the Owner, some the FavoriteToy, etc. Of course, you could call Load() for each reference you need anytime you need one. But that will generate a call to the database each time. Bad idea. So instead, each page will ask for the data it wants to see when it first request for the Dog object: static public Dog Get(int id) { return GetDog(entity,"");} static public Dog Get(int id, string includePath) { string query = "select value o " + " from YourEntities.DogSet as o " +

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  • JNI Method not found

    - by Select Call
    I have been receiving this error for my JNI code while I tried find the method ,using GetMethodID, my Java method is in an Interface. Here is my interface public interface printReader { public printImg readerPrint(String selectedName) throws Exception; } Native code WprintImgIMPL.h class WprintImgIMPL: public IWprintReader { public: WprintImgIMPL(JNIEnv *env, jobject obj); ~WprintImgIMPL(void); virtual WprintImg readerPrint(char* readerName) ; ..... ..... private: JNIEnv *m_Env; jobject m_jObj; } WprintImgIMPL.cpp WprintImg WprintImgIMPL::readerPrint(char* readerName) { jclass cls = m_Env->GetObjectClass (m_jObj); jmethodID mid = m_Env->GetMethodID (cls, "readerPrint", "(Ljava/lang/String;)Lcom/site/name/printImg;"); ....... ....... } Java code public class printReaderIMPL implements printReader { static final String DEBUG_TAG = ""; android.net.wifi.WifiManager.MulticastLock lock; Context _context; public printReaderIMPL (Context context) { _context = context; } @Override public printImg readerPrint(String selectedName) throws Exception { Log.e(DEBUG_TAG, "readerPrint"); } } Constructor/destructor WprintImgIMPL(JNIEnv *env, jobject obj){ m_Env = env; m_jobj = env->NewGlobalRef(obj); } ~WprintImgIMPL(void) { m_Env->DeleteGlobalRef(m_jobj); } Error: GetMethodID: method not found: Lcom/site/name/NativeCode;.printImg:(Ljava/lang/String;)Lcom/site/name/printImg; Signature are checked twice , after failure I generated again using Javap tool . Thank you if you can input /comment and help in fixing this bug.

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  • Tools to Help Post Content On Your WordPress Blog

    - by Matthew Guay
    Now that you’ve got a nice blog, you want to do more with it and start posting content.  Here we look at some tools that will allow you to post directly to your WordPress blog. Writing a new blog post is easy with WordPress as we saw in our previous post about Starting your own WordPress blog.  The web editor gives you a lot of features and even lets you edit your post’s source code if you enjoy hacking HTML.  There are other tools that will allow you to post content, here we look at how you can post with dedicated apps, browser plugins, and even by email. Windows Live Writer Windows Live Writer (part of the Windows Live Essentials Suite) is a great app for posting content to your blog.  This free program for Microsoft lets you post content to a variety of blogging services, including Blogger, Typepad, LiveJournal, and of course WordPress.  You can write blog posts directly from its Word-like editor, complete with pictures and advanced formatting.  Even if you’re offline, you can still write posts and save them for when you’re online again. For more information about installing Live writer, check out our article on how to Install Windows Live Essentials In Windows 7. Once Live Writer is installed, open it to add your blog.  If you already had Live Writer installed and configured for a blog, you can add your new blog, too.  Just click your blog’s name in the top right corner, and select “Add blog account”. Select “Other blog service” to add your WordPress blog to Writer, and click Next.   Enter your blog’s web address, and your username and password.  Check Remember my password so you don’t have to enter it every time you write something. Writer will analyze your blog and setup your account. During the setup process it may ask to post a temporary post.  This will let you preview blog posts using your blog’s real theme, which is helpful, so click Yes. Finally, add your Blog’s name, and click Finish. You can now use the rich editor to write and add content to a new blog post.   Select the Preview tab to see how your post will look on your blog… Or, if you’re a HTML geek, select the Source tab to edit the code of your blog post. From the bottom of the window, you can choose categories, insert tags, and even schedule the post to publish on a different day.  Live Writer is fully integrated with WordPress; you’re not missing anything by using the desktop editor. If you want to edit a post you’ve already published, click the Open button and select the post.  You can chose and edit any post, including ones you published via the web interface or other editors. Add Multimedia Content to your Posts with Live Writer Back in the Edit tab, you can add pictures, videos and more from the sidebar.  Select what you want to insert. Pictures If you insert a picture, you can add many nice borders and designs to it. Or, you can even add artistic effects from the Effects tab in the sidebar. Photo Gallery If you want to post several pictures, say some of your vacation shots, then inserting a picture gallery may be the best option.  Select Insert Photo Gallery in the sidebar, and then choose the pictures you want in the gallery. Once the gallery is inserted, you can choose from several styles to showcase your pictures. When you post the blog, you will be asked to sign in with your Windows Live ID as the gallery pictures will be stored in the free Skydrive storage service. Your blog readers can see the preview of your pictures directly on your blog, and then can view each individual picture, download them, or see a slideshow online via the link. Video If you want to add a video to your blog post, select Video from the sidebar as above.  You can select a video that’s already online, or you can choose a new video from file and upload it via YouTube directly from Windows Live Writer.   Note that you will have to sign in with your YouTube account to upload videos to YouTube, so if you’re not logged in you’ll be prompted to do so when you click Insert. Geek Tip:  If you ever want to copy your Live Writer settings to another computer, check out our article on how to Backup Your Windows Live Writer Settings. Microsoft Office Word Word 2007 and 2010 also let you post content directly to your blog.  This is especially nice if you’ve already typed up a document and think it would be good on your Blog as well.  Check out our in-depth tutorial on posting blog posts via Word 2007 using Word 2007 as a blogging tool. This works in Word 2010 too, except the Office Orb has been replaced by the new Backstage view.  So, in Word 2010, to start a new blog post, click File \ New then select Blog post.  Proceed as you would in Word 2007 to add your blog settings and post the content you want. Or, if you’ve already written a document and want to post it, select File \ Share (or Save and Send in the final version of Word 2010), and then click Publish as Blog Post.  If you haven’t setup your blog account yet, set it up as shown in the Word 2007 article. Post Via Email Most of us use email daily, and already have our favorite email app or service.  Whether on your desktop or mobile phone, it’s easy to create rich emails and add content.  WordPress lets you generate a unique email address that you can use to easily post content and email to your blog.  Just compose your email with the subject as the title of your post, and send it to this unique address.  Your new post will be up in minutes. To active this feature, click the My Account button in the top menu bar in your WordPress.com account, and select My Blogs. Click the Enable button under Post by Email beside your blog’s name.   Now you’ll have a private email you can use to post to your blog.  Anything you send to this email will be posted as a new post.  If you think your email may be compromised, click Regenerate to get a new publishing email address. Any email program or webapp now is a blog post editor.  Feel free to use rich formatting or insert pictures; it all comes through great.  This is also a great way to post to your blog from your mobile device.  Whether you’re using webmail or a dedicated email client on your phone, you can now blog from anywhere.   Mobile Applications WordPress also offer dedicated applications for blogging directly from your mobile device.  You can write new posts, edit existing ones, and manage comments all from your Smartphone.  Currently they offer apps for iPhone, Android, and Blackberry.  Check them out at the link below. Conclusion Whether you want to write from your browser or email a post to your blog, WordPress is flexible enough to work right along with your preferences.  However you post, you can be sure that it will look professional and be easily accessible with your WordPress blog. Download Windows Live Writer Download WordPress apps for your mobile device Similar Articles Productive Geek Tips Quick Tip: Set a Future Date for a Post in WordPressAdd Social Bookmarking (Digg This!) Links to your Wordpress BlogFuture Date a Post in Windows Live WriterHow To Start Your Own Professional Blog with WordPressUsing Word 2007 as a Blogging Tool TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Acronis Online Backup DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows Fun with 47 charts and graphs Tomorrow is Mother’s Day Check the Average Speed of YouTube Videos You’ve Watched OutlookStatView Scans and Displays General Usage Statistics How to Add Exceptions to the Windows Firewall Office 2010 reviewed in depth by Ed Bott

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  • Customize the Five Windows Folder Templates

    - by Mark Virtue
    Are you’re particular about the way Windows Explorer presents each folder’s contents? Here we show you how to take advantage of Explorer’s built-in templates, which cuts down the time it takes to do customizations. Note: The techniques in this article apply to Windows XP, Vista, and Windows 7. When opening a folder for the first time in Windows Explorer, we are presented with a standard default view of the files and folders in that folder. It may be that the items are presented are perfectly fine, but on the other hand, we may want to customize the view.  The aspects of it that we can customize are the following: The display type (list view, details, tiles, thumbnails, etc) Which columns are displayed, and in which order The widths of the visible columns The order in which the files and folders are sorted Any file groupings Thankfully, Windows offers us a shortcut.  A particular folder’s settings can be used as a “template” for other, similar folders.  In fact, we can store up to five separate sets of folder presentation configurations.  Once we save the settings for a particular template, that template can then be applied to other folders. Customize Your First Folder We’ll start by setting up the first of our templates – the default one.  Once we create this template and apply it, the vast majority of the folders in our file system will change to match it, so it’s important that we set it up very carefully.  The first step in creating and applying the template is to customize one folder with the settings that all the rest will have. Choose a folder that is typical of the folders that you wish to have this default template.  Select it in Windows Explorer.  To ensure that it is a suitable candidate, right-click the folder name and select Properties, then go to the Customize tab.  Ensure that this folder is marked as General Items.  If it is not, either choose a different folder or select General Items from the list. Click OK.  Now we’re ready to customize our first folder. Changing the way one single folder is presented is straightforward.  We start with the folder’s display type.  Click the Change your view button in the top-right corner of every Explorer window. Each time you click the button, the folder’s view cycles to the next view type.  Alternatively you can click the little down-arrow next to the button to see all the display types at once, and select the one you want. Click the view you want, or drag the slider next to the one you want. If you have chosen Details, then the next thing you may wish to change is which columns are displayed, and the order of these.  To choose which columns are displayed, simply right-click on any column heading.  A list of the columns currently being display appears. Simply uncheck a column if you don’t want it displayed, and check the columns that you want displayed.  If you want some information displayed about your files that is not listed here, then click the More… button for a full list of file attributes. There’s a lot of them! To change the order of the columns that are currently being displayed, simply click on a column heading and drag it to where you think it should be.  To change the width of a column, click the line that represents the right-hand edge of the column and drag it left or right. To sort by a column, click once on that column.  To reverse the sort-order, click that same column again. To change the groupings of the files in the folder, right-click in a blank area of the folder, select Group by, and select the appropriate column. Apply This Default Template to All Similar Folders Once you have the folder exactly the way you want it, we now use this folder as our default template for most of the folders in our file system.  To do this, ensure that you are still in the folder you just customized, and then, from the Organize menu in Explorer, click on Folder and search options. Then select the View tab and click the Apply to Folders button. After you’ve clicked OK, visit some of the other folders in your file system.  You should see that most have taken on these new settings. What we’ve just done, in effect, is we have customized the General Items template.  This is one of five templates that Windows Explorer uses to display folder contents.  The five templates are called (in Windows 7): General Items Documents Pictures Music Videos When a folder is opened, Windows Explorer examines the contents to see if it can automatically determine which folder template to use to display the folder contents.  If it is not obvious that the folder contents falls into any of the last four templates, then Windows Explorer chooses the General Items template.  That’s why most of the folders in your file system are shown using the General Items template. Changing the Other Four Templates If you want to adjust the other four templates, the process is very similar to what we’ve just done.  If you wanted to change the “Music” template, for example, the steps would be as follows: Select a folder that contains music items Apply the existing Music template to the folder (even if it doesn’t look like you want it to) Customize the folder to your personal preferences Apply the new template to all “Music” folders A fifth step would be:  When you open a folder that contains music items but is not automatically displayed using the Music template, you manually select the Music template for that folder. First, select a folder that contains music items.  It will probably be displayed using the existing Music template: Next, ensure that it is using the Music template.  If it’s not, then manually select the Music template. Next, customize the folder to suit your personal preferences (here we’ve added a couple of columns, and sorted by Artist). Now we can set this view to be our Music template.  Choose Organize, then the View tab, and click the Apply to Folders button. Note: The only folders that will inherit these settings are the ones that are currently (or will soon be) using the Music template. Now, if you have any folder that contains music items, and you want it to inherit all of these settings, then right-click the folder name, choose Properties, and select that this folder should use the Music template.  You can also cehck the box entitled Also apply this template to all subfolders if you want to save yourself even more time with all the sub-folders. Conclusion It’s neat to be able to set up templates for your folder views like this.  It’s a shame that Microsoft didn’t take the concept just a little further and allow you to create as many templates as you want. Similar Articles Productive Geek Tips Fix For When Windows Explorer in Vista Stops Showing File NamesCustomize the Windows 7 or Vista Send To MenuFix for New Contact Group Button Not Displaying in VistaWhy Did Windows Vista’s Music Folder Icon Turn Yellow?Make Your Last Minute Holiday Cards with Microsoft Word TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Office 2010 reviewed in depth by Ed Bott FoxClocks adds World Times in your Statusbar (Firefox) Have Fun Editing Photo Editing with Citrify Outlook Connector Upgrade Error Gadfly is a cool Twitter/Silverlight app Enable DreamScene in Windows 7

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  • SQL Server Split() Function

    - by HighAltitudeCoder
    Title goes here   Ever wanted a dbo.Split() function, but not had the time to debug it completely?  Let me guess - you are probably working on a stored procedure with 50 or more parameters; two or three of them are parameters of differing types, while the other 47 or so all of the same type (id1, id2, id3, id4, id5...).  Worse, you've found several other similar stored procedures with the ONLY DIFFERENCE being the number of like parameters taped to the end of the parameter list. If this is the situation you find yourself in now, you may be wondering, "why am I working with three different copies of what is basically the same stored procedure, and why am I having to maintain changes in three different places?  Can't I have one stored procedure that accomplishes the job of all three? My answer to you: YES!  Here is the Split() function I've created.    /******************************************************************************                                       Split.sql   ******************************************************************************/ /******************************************************************************   Split a delimited string into sub-components and return them as a table.   Parameter 1: Input string which is to be split into parts. Parameter 2: Delimiter which determines the split points in input string. Works with space or spaces as delimiter. Split() is apostrophe-safe.   SYNTAX: SELECT * FROM Split('Dvorak,Debussy,Chopin,Holst', ',') SELECT * FROM Split('Denver|Seattle|San Diego|New York', '|') SELECT * FROM Split('Denver is the super-awesomest city of them all.', ' ')   ******************************************************************************/ USE AdventureWorks GO   IF EXISTS       (SELECT *       FROM sysobjects       WHERE xtype = 'TF'       AND name = 'Split'       ) BEGIN       DROP FUNCTION Split END GO   CREATE FUNCTION Split (       @InputString                  VARCHAR(8000),       @Delimiter                    VARCHAR(50) )   RETURNS @Items TABLE (       Item                          VARCHAR(8000) )   AS BEGIN       IF @Delimiter = ' '       BEGIN             SET @Delimiter = ','             SET @InputString = REPLACE(@InputString, ' ', @Delimiter)       END         IF (@Delimiter IS NULL OR @Delimiter = '')             SET @Delimiter = ','   --INSERT INTO @Items VALUES (@Delimiter) -- Diagnostic --INSERT INTO @Items VALUES (@InputString) -- Diagnostic         DECLARE @Item                 VARCHAR(8000)       DECLARE @ItemList       VARCHAR(8000)       DECLARE @DelimIndex     INT         SET @ItemList = @InputString       SET @DelimIndex = CHARINDEX(@Delimiter, @ItemList, 0)       WHILE (@DelimIndex != 0)       BEGIN             SET @Item = SUBSTRING(@ItemList, 0, @DelimIndex)             INSERT INTO @Items VALUES (@Item)               -- Set @ItemList = @ItemList minus one less item             SET @ItemList = SUBSTRING(@ItemList, @DelimIndex+1, LEN(@ItemList)-@DelimIndex)             SET @DelimIndex = CHARINDEX(@Delimiter, @ItemList, 0)       END -- End WHILE         IF @Item IS NOT NULL -- At least one delimiter was encountered in @InputString       BEGIN             SET @Item = @ItemList             INSERT INTO @Items VALUES (@Item)       END         -- No delimiters were encountered in @InputString, so just return @InputString       ELSE INSERT INTO @Items VALUES (@InputString)         RETURN   END -- End Function GO   ---- Set Permissions --GRANT SELECT ON Split TO UserRole1 --GRANT SELECT ON Split TO UserRole2 --GO   The syntax is basically as follows: SELECT <fields> FROM Table 1 JOIN Table 2 ON ... JOIN Table 3 ON ... WHERE LOGICAL CONDITION A AND LOGICAL CONDITION B AND LOGICAL CONDITION C AND TABLE2.Id IN (SELECT * FROM Split(@IdList, ',')) @IdList is a parameter passed into the stored procedure, and the comma (',') is the delimiter you have chosen to split the parameter list on. You can also use it like this: SELECT <fields> FROM Table 1 JOIN Table 2 ON ... JOIN Table 3 ON ... WHERE LOGICAL CONDITION A AND LOGICAL CONDITION B AND LOGICAL CONDITION C HAVING COUNT(SELECT * FROM Split(@IdList, ',') Similarly, it can be used in other aggregate functions at run-time: SELECT MIN(SELECT * FROM Split(@IdList, ','), <fields> FROM Table 1 JOIN Table 2 ON ... JOIN Table 3 ON ... WHERE LOGICAL CONDITION A AND LOGICAL CONDITION B AND LOGICAL CONDITION C GROUP BY <fields> Now that I've (hopefully effectively) explained the benefits to using this function and implementing it in one or more of your database objects, let me warn you of a caveat that you are likely to encounter.  You may have a team member who waits until the right moment to ask you a pointed question: "Doesn't this function just do the same thing as using the IN function?  Why didn't you just use that instead?  In other words, why bother with this function?" What's happening is, one or more team members has failed to understand the reason for implementing this kind of function in the first place.  (Note: this is THE MOST IMPORTANT ASPECT OF THIS POST). Allow me to outline a few pros to implementing this function, so you may effectively parry this question.  Touche. 1) Code consolidation.  You don't have to maintain what is basically the same code and logic, but with varying numbers of the same parameter in several SQL objects.  I'm not going to go into the cons related to using this function, because the afore mentioned team member is probably more than adept at pointing these out.  Remember, the real positive contribution is ou are decreasing the liklihood that your team fails to update all (x) duplicate copies of what are basically the same stored procedure, and so on...  This is the classic downside to duplicate code.  It is a virus, and you should kill it. You might be better off rejecting your team member's question, and responding with your own: "Would you rather maintain the same logic in multiple different stored procedures, and hope that the team doesn't forget to always update all of them at the same time?".  In his head, he might be thinking "yes, I would like to maintain several different copies of the same stored procedure", although you probably will not get such a direct response.  2) Added flexibility - you can use the Split function elsewhere, and for splitting your data in different ways.  Plus, you can use any kind of delimiter you wish.  How can you know today the ways in which you might want to examine your data tomorrow?  Segue to my next point. 3) Because the function takes a delimiter parameter, you can split the data in any number of ways.  This greatly increases the utility of such a function and enables your team to work with the data in a variety of different ways in the future.  You can split on a single char, symbol, word, or group of words.  You can split on spaces.  (The list goes on... test it out). Finally, you can dynamically define the behavior of a stored procedure (or other SQL object) at run time, through the use of this function.  Rather than have several objects that accomplish almost the same thing, why not have only one instead?

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  • Change default language settings in Visual Studio 2012

    - by sreejukg
    The first thing you need to do after the installation of Visual Studio 2012 is to choose the IDE preferences. Once you select your preferred collection of settings, the IDE will always choose dialogs and other options according to your selection. Nowadays developer’s needs to work with different programming environments and due to this, developers might need to reset the default settings. In this article, I am going to demonstrate how you can change the default settings in Visual Studio 2012. For the purpose of this demonstration, I have installed Visual Studio 2012 and selected C++ as my default environment settings. So now when I go to file -> new project, it will give me C++ templates by default as follows. If you want to select another language, you need to expand Other Languages section and select C# or VB. Now I am going to change these default settings. I am going to change the default language preference to C#. In Visual Studio 2012, go to tools menu and select Import and Export Settings. Here you have 3 options; one is to export the current settings so that the settings are saved for future use. Also you can import previously saved settings. The last option available is to reset it to default. It is a good Idea to export your settings and import it as you need in later stages. To reset the settings to default select the Reset option and click next. Now Visual Studio will ask you to whether you would like to save the settings, which can be used in future to restore. Select any one option and click next. For the purpose of this demo, I have selected not to save the settings. Click Next button to continue. Now Visual Studio will bring you the similar dialog that appears just after installation to select your IDE settings. Select the required settings from the available list and click Finish button. Click Finish once you are done. If everything OK, you will see the success message as below. Now go to file -> new Project, you will see the selected language appear by default. I selected C# in the previous step and the new project dialog appears as follows. Changing IDE settings in Visual Studio 2012 is very easy and straight forward.

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  • Calling Web Services using ADF 11g

    - by James Taylor
    One of the benefits of ADF is that fact that it can use multiple data sources. With SOA playing a big part in today’s IT landscape, applications need to be able to utilise this SOA framework to leverage functionality from multiple systems to provide a composite application. ADF provides functionality to expose web services via the ADF Business Component so if you know how to use Business Components for a database. Configuring ADF for web services is much the same. In this example I use an OSB web service that gets a customer. Create a new Fusion Web Application (ADF) Application and click OK    Provide an Application Name, GetCustomerADF and click Next    From the Project Technologies move Web Services into the Selected box. Accept the defaults and click Finish. Right-click the Model project and select New In the Gallery select Web Services –> Web Service Data Control then click OK. Provide a name GetCustomerDC and give the URL endpoint for the Web Service, then click Next Select the web service operation you want to use for the ADF application. In my example my web service only has one operation. Click Finish Save your work, File –> Save The data control has now been created, the next steps create the UI components. In your application created in step 1 find the ViewController project, right-click and choose New In the Gallery select JSF –> JSF Page Provide a name for the jsp page, GetCustomer, Also ensure that the ‘Create as XML Document (*.jsp) check box is checked. I have selected the page template, Oracle Three Column Layout but you can create a layout of your choice. I only want 2 columns so I delete the last column but right-clicking the right had panel and selecting Delete Drag the fields you require from the web service data control to the left pannel. In my example I only require the Customer ID. When you drag to the panel select Texts –>ADF Input Text w/Label In this example I want to search on a customer based on the ID. So Once I select the ID I want to execute the request. To do this I need a button. Drag the operation object under the fields created in step 15. Select Methods –> ADF Button. You now need to provide the mappings, Choose the ‘Show EI Expression Builder’ Navigate to the bindings, ADFBindings –> bindings –> parametersIterator –> currentRow Click OK Drag and drop the return information I just want the results shown in a form. I want to show all fields Now it is time to test, Right-click the jspx page created in steps 11 – 21 and select Run A browser should start, enter valid values and test  

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  • Customize the Background in Boxee

    - by DigitalGeekery
    Are you a Boxee user who thinks the default background is little boring? Today we’ll take a look at how to freshen up the look of Boxee by changing the background. Boxee Background When you log into Boxee, select the Settings button at the upper left corner of the Home page.   Select General on the Settings screen. When you select or hover your mouse over the Background Image button, you’ll see options to set a background image or set a background image folder. You’ll have the option of settings a single static image as your background, or choosing an images folder.   If you choose a folder, Boxee will rotate through the images in the folder. To set Background images folder, select that option. Browse for your image folder.. And then select OK.   Boxee will rotate through the images in the folder.   Images will change every ten seconds.   If you prefer a single static image, select Set background image   Choose a image and select OK. Now just enjoy you nice new backgrounds.   If you ever wish to revert back to the default Boxee background, simply select Reset Images on the Settings \ General screen. Adding your own backgrounds is a nice way to customize your Boxee experience. Ideally, you’ll want to choose high resolution images and images oriented as landscape rather than portrait. If you are unfamiliar with Boxee, check out our article on getting started with Boxee.  Looking for a Boxee remote? Read how to use your iPhone or iPod Touch as a Boxee remote. Similar Articles Productive Geek Tips Integrate Boxee with Media Center in Windows 7Using Pandora in BoxeeWatch Netflix Instant Movies in BoxeeUse your iPhone or iPod Touch as a Boxee RemoteCustomize the Windows 7 Logon Screen TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Snagit 10 Use ILovePDF To Split and Merge PDF Files TimeToMeet is a Simple Online Meeting Planning Tool Easily Create More Bookmark Toolbars in Firefox Filevo is a Cool File Hosting & Sharing Site Get a free copy of WinUtilities Pro 2010 World Cup Schedule

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  • Sniffing out SQL Code Smells: Inconsistent use of Symbolic names and Datatypes

    - by Phil Factor
    It is an awkward feeling. You’ve just delivered a database application that seems to be working fine in production, and you just run a few checks on it. You discover that there is a potential bug that, out of sheer good chance, hasn’t kicked in to produce an error; but it lurks, like a smoking bomb. Worse, maybe you find that the bug has started its evil work of corrupting the data, but in ways that nobody has, so far detected. You investigate, and find the damage. You are somehow going to have to repair it. Yes, it still very occasionally happens to me. It is not a nice feeling, and I do anything I can to prevent it happening. That’s why I’m interested in SQL code smells. SQL Code Smells aren’t necessarily bad practices, but just show you where to focus your attention when checking an application. Sometimes with databases the bugs can be subtle. SQL is rather like HTML: the language does its best to try to carry out your wishes, rather than to be picky about your bugs. Most of the time, this is a great benefit, but not always. One particular place where this can be detrimental is where you have implicit conversion between different data types. Most of the time it is completely harmless but we’re  concerned about the occasional time it isn’t. Let’s give an example: String truncation. Let’s give another even more frightening one, rounding errors on assignment to a number of different precision. Each requires a blog-post to explain in detail and I’m not now going to try. Just remember that it is not always a good idea to assign data to variables, parameters or even columns when they aren’t the same datatype, especially if you are relying on implicit conversion to work its magic.For details of the problem and the consequences, see here:  SR0014: Data loss might occur when casting from {Type1} to {Type2} . For any experienced Database Developer, this is a more frightening read than a Vampire Story. This is why one of the SQL Code Smells that makes me edgy, in my own or other peoples’ code, is to see parameters, variables and columns that have the same names and different datatypes. Whereas quite a lot of this is perfectly normal and natural, you need to check in case one of two things have gone wrong. Either sloppy naming, or mixed datatypes. Sure it is hard to remember whether you decided that the length of a log entry was 80 or 100 characters long, or the precision of a number. That is why a little check like this I’m going to show you is excellent for tidying up your code before you check it back into source Control! 1/ Checking Parameters only If you were just going to check parameters, you might just do this. It simply groups all the parameters, either input or output, of all the routines (e.g. stored procedures or functions) by their name and checks to see, in the HAVING clause, whether their data types are all the same. If not, it lists all the examples and their origin (the routine) Even this little check can occasionally be scarily revealing. ;WITH userParameter AS  ( SELECT   c.NAME AS ParameterName,  OBJECT_SCHEMA_NAME(c.object_ID) + '.' + OBJECT_NAME(c.object_ID) AS ObjectName,  t.name + ' '     + CASE     --we may have to put in the length            WHEN t.name IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN c.max_length = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN t.name IN ('nchar', 'nvarchar')                      THEN c.max_length / 2 ELSE c.max_length                    END)                END + ')'         WHEN t.name IN ('decimal', 'numeric')             THEN '(' + CONVERT(VARCHAR(4), c.precision)                   + ',' + CONVERT(VARCHAR(4), c.Scale) + ')'         ELSE ''      END  --we've done with putting in the length      + CASE WHEN XML_collection_ID <> 0         THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                    THEN 'DOCUMENT '                    ELSE 'CONTENT '                   END              + COALESCE(               (SELECT QUOTENAME(ss.name) + '.' + QUOTENAME(sc.name)                FROM sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE sc.xml_collection_ID = c.XML_collection_ID),'NULL') + ')'          ELSE ''         END        AS [DataType]  FROM sys.parameters c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys'   AND parameter_id>0)SELECT CONVERT(CHAR(80),objectName+'.'+ParameterName),DataType FROM UserParameterWHERE ParameterName IN   (SELECT ParameterName FROM UserParameter    GROUP BY ParameterName    HAVING MIN(Datatype)<>MAX(DataType))ORDER BY ParameterName   so, in a very small example here, we have a @ClosingDelimiter variable that is only CHAR(1) when, by the looks of it, it should be up to ten characters long, or even worse, a function that should be a char(1) and seems to let in a string of ten characters. Worth investigating. Then we have a @Comment variable that can't decide whether it is a VARCHAR(2000) or a VARCHAR(MAX) 2/ Columns and Parameters Actually, once we’ve cleared up the mess we’ve made of our parameter-naming in the database we’re inspecting, we’re going to be more interested in listing both columns and parameters. We can do this by modifying the routine to list columns as well as parameters. Because of the slight complexity of creating the string version of the datatypes, we will create a fake table of both columns and parameters so that they can both be processed the same way. After all, we want the datatypes to match Unfortunately, parameters do not expose all the attributes we are interested in, such as whether they are nullable (oh yes, subtle bugs happen if this isn’t consistent for a datatype). We’ll have to leave them out for this check. Voila! A slight modification of the first routine ;WITH userObject AS  ( SELECT   Name AS DataName,--the actual name of the parameter or column ('@' removed)  --and the qualified object name of the routine  OBJECT_SCHEMA_NAME(ObjectID) + '.' + OBJECT_NAME(ObjectID) AS ObjectName,  --now the harder bit: the definition of the datatype.  TypeName + ' '     + CASE     --we may have to put in the length. e.g. CHAR (10)           WHEN TypeName IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN MaxLength = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN TypeName IN ('nchar', 'nvarchar')                      THEN MaxLength / 2 ELSE MaxLength                    END)                END + ')'         WHEN TypeName IN ('decimal', 'numeric')--a BCD number!             THEN '(' + CONVERT(VARCHAR(4), Precision)                   + ',' + CONVERT(VARCHAR(4), Scale) + ')'         ELSE ''      END  --we've done with putting in the length      + CASE WHEN XML_collection_ID <> 0 --tush tush. XML         THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                    THEN 'DOCUMENT '                    ELSE 'CONTENT '                   END              + COALESCE(               (SELECT TOP 1 QUOTENAME(ss.name) + '.' + QUOTENAME(sc.Name)                FROM sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE sc.xml_collection_ID = XML_collection_ID),'NULL') + ')'          ELSE ''         END        AS [DataType],       DataObjectType  FROM   (Select t.name AS TypeName, REPLACE(c.name,'@','') AS Name,          c.max_length AS MaxLength, c.precision AS [Precision],           c.scale AS [Scale], c.[Object_id] AS ObjectID, XML_collection_ID,          is_XML_Document,'P' AS DataobjectType  FROM sys.parameters c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  AND parameter_id>0  UNION all  Select t.name AS TypeName, c.name AS Name, c.max_length AS MaxLength,          c.precision AS [Precision], c.scale AS [Scale],          c.[Object_id] AS ObjectID, XML_collection_ID,is_XML_Document,          'C' AS DataobjectType            FROM sys.columns c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID   WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys'  )f)SELECT CONVERT(CHAR(80),objectName+'.'   + CASE WHEN DataobjectType ='P' THEN '@' ELSE '' END + DataName),DataType FROM UserObjectWHERE DataName IN   (SELECT DataName FROM UserObject   GROUP BY DataName    HAVING MIN(Datatype)<>MAX(DataType))ORDER BY DataName     Hmm. I can tell you I found quite a few minor issues with the various tabases I tested this on, and found some potential bugs that really leap out at you from the results. Here is the start of the result for AdventureWorks. Yes, AccountNumber is, for some reason, a Varchar(10) in the Customer table. Hmm. odd. Why is a city fifty characters long in that view?  The idea of the description of a colour being 256 characters long seems over-ambitious. Go down the list and you'll spot other mistakes. There are no bugs, but just mess. We started out with a listing to examine parameters, then we mixed parameters and columns. Our last listing is for a slightly more in-depth look at table columns. You’ll notice that we’ve delibarately removed the indication of whether a column is persisted, or is an identity column because that gives us false positives for our code smells. If you just want to browse your metadata for other reasons (and it can quite help in some circumstances) then uncomment them! ;WITH userColumns AS  ( SELECT   c.NAME AS columnName,  OBJECT_SCHEMA_NAME(c.object_ID) + '.' + OBJECT_NAME(c.object_ID) AS ObjectName,  REPLACE(t.name + ' '   + CASE WHEN is_computed = 1 THEN ' AS ' + --do DDL for a computed column          (SELECT definition FROM sys.computed_columns cc           WHERE cc.object_id = c.object_id AND cc.column_ID = c.column_ID)     --we may have to put in the length            WHEN t.Name IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN c.Max_Length = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN t.Name IN ('nchar', 'nvarchar')                      THEN c.Max_Length / 2 ELSE c.Max_Length                    END)                END + ')'       WHEN t.name IN ('decimal', 'numeric')       THEN '(' + CONVERT(VARCHAR(4), c.precision) + ',' + CONVERT(VARCHAR(4), c.Scale) + ')'       ELSE ''      END + CASE WHEN c.is_rowguidcol = 1          THEN ' ROWGUIDCOL'          ELSE ''         END + CASE WHEN XML_collection_ID <> 0            THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                THEN 'DOCUMENT '                ELSE 'CONTENT '               END + COALESCE((SELECT                QUOTENAME(ss.name) + '.' + QUOTENAME(sc.name)                FROM                sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE                sc.xml_collection_ID = c.XML_collection_ID),                'NULL') + ')'            ELSE ''           END + CASE WHEN is_identity = 1             THEN CASE WHEN OBJECTPROPERTY(object_id,                'IsUserTable') = 1 AND COLUMNPROPERTY(object_id,                c.name,                'IsIDNotForRepl') = 0 AND OBJECTPROPERTY(object_id,                'IsMSShipped') = 0                THEN ''                ELSE ' NOT FOR REPLICATION '               END             ELSE ''            END + CASE WHEN c.is_nullable = 0               THEN ' NOT NULL'               ELSE ' NULL'              END + CASE                WHEN c.default_object_id <> 0                THEN ' DEFAULT ' + object_Definition(c.default_object_id)                ELSE ''               END + CASE                WHEN c.collation_name IS NULL                THEN ''                WHEN c.collation_name <> (SELECT                collation_name                FROM                sys.databases                WHERE                name = DB_NAME()) COLLATE Latin1_General_CI_AS                THEN COALESCE(' COLLATE ' + c.collation_name,                '')                ELSE ''                END,'  ',' ') AS [DataType]FROM sys.columns c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys')SELECT CONVERT(CHAR(80),objectName+'.'+columnName),DataType FROM UserColumnsWHERE columnName IN (SELECT columnName FROM UserColumns  GROUP BY columnName  HAVING MIN(Datatype)<>MAX(DataType))ORDER BY columnName If you take a look down the results against Adventureworks, you'll see once again that there are things to investigate, mostly, in the illustration, discrepancies between null and non-null datatypes So I here you ask, what about temporary variables within routines? If ever there was a source of elusive bugs, you'll find it there. Sadly, these temporary variables are not stored in the metadata so we'll have to find a more subtle way of flushing these out, and that will, I'm afraid, have to wait!

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  • SCCM 2007 Collections per OU

    - by VirtualizeIT
    Recently I wanted to create our SCCM collections setup as our Active Directory structure. I finally figured out how to create collections per OU of the domain. I decided to create a simple tutorial that may help other IT professionals the steps to complete this task.   1. Open the ConfigMgr and navigation to the collections. To navigate to the collections go to Site Database>Computer Management>Collections. 2. In the ‘Collections’ right-click and select New Collections. Then it will pop up a Wizards so you can enter the name of the collection and any notes that you may want to add that is associated with the collection.                       3. Next, select the database icon. In the ‘Name’ textbox enter the name of the query. I named mine ‘Query’ just for simplicity sake. After you enter the name select ‘Edit Query Statement…’ 4. Select the ‘Criteria’ tab 5. Select the icon that looks like a sun. 6. At this point you should see a dialog box like this…                     7. Next, click the ‘select’ button. 8. Under the ‘Attribute class’ scroll through until you see ’System Resource’ and for the ‘Attribute"’ scroll through you see ‘System OU Name’. It should look something like this…                 9. After that select OK. 10. In the ‘Value’ textbox enter the string that is associated with the OU in your domain. NOTE: If you don’t know your string name for your OU you can simply go to “Active Directory Users and Computers” and right-click on the OU and select properties. In the ‘object’ tab you should see the string under the ‘Canonical name of object”. That is the string that you put in the ‘Value’ text box. 11. After you enter the OU string name press OK>OK>OK>NEXT>NEXT>FINISH.   That’s it!   I hope this tutorial has help you understand how to create a collection through your OU structure.

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