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  • SQLite doesn't have booleans or date-times...but C# does

    - by DanM
    I've been thinking about using SQLite for my next project, but I'm concerned that it seems to lack proper datetime and bit data types. If I use DbLinq (or some other ORM) to generate C# classes, will the data types of the properties be "dumbed down"? Will date-time data be placed in properties of type string or double? Will boolean data be placed in properties of type int? If yes, what are the implications? I'm envisioning a scenario where I need to write a whole second layer of classes with more specific data types and do a bunch of transformations and casts, but maybe it's not so bad. If you have any experience with this or a similar scenario, what are your "lessons learned"?

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  • How to pass interface type/GUID reference to an automation method in Delphi

    - by Alan Clark
    In Delphi you can pass class references around to compare the types of objects, and to instantiate them. Can you do the same with interface references being passed to a COM automation server? For example, you can define a method taking a GUID parameter using the type library editor: function ChildNodesOfType(NodeType: TGUID): IMBNode; safecall; In this function I would like to return automation types that support the interface specified by NodeType, e.g. if Supports(SomeNode, NodeType) then result := SomeNode; But the Supports call always fails, I tried passing in the Guids defined in the type library but none of the different types (Ixxx, Class_xxxx, IId_Ixxxx) seem to work.

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  • How to JSON serialize math vector type in F#?

    - by The_Ghost
    Hello! I'm trying to serialize "vector" (Microsoft.FSharp.Math) type. And I get that error: Exception Details: System.Runtime.Serialization.SerializationException: Type 'Microsoft.FSharp.Math.Instances+FloatNumerics@115' with data contract name 'Instances.FloatNumerics_x0040_115:http://schemas.datacontract.org/2004/07/Microsoft.FSharp.Math' is not expected. Add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer. I have tried to put KnownType attribute and some other stuff, but nothing helps! Could someone know the answer? This is the code I use: // [< KnownType( typeof<vector> ) >] type MyType = vector let public writeTest = let aaa = vector [1.1;2.2] let serializer = new DataContractJsonSerializer( typeof<MyType> ) let writer = new StreamWriter( @"c:\test.txt" ) serializer.WriteObject(writer.BaseStream, aaa) writer.Close()

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  • How can one use the "Add view" dialog in Visual Studio efficiently when working with ASP.NET MVC?

    - by Marek
    Does anyone else think that the add view dialog in VS is useless or is it just me? Why is there no search/filtering in there? I can not even paste the type name (without namespace) there to speed up the view creation. Plus, there are a lot of irrelevant classes there, including classes from all referenced libraries. Am I missing something or Microsoft never did any usability testing with that?? Is it possible to filter out types/assemblies in the dialog and/or better navigation compared to manually scrolling the combobox with all the types listed? Is it possible to include only types from a particular directory/assembly/namespace? (the ViewModels namespace for example) EDIT: As it seems from the answers that there is no usable workaround for this, I have filed a suggestion at Connect: https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=507784 Please vote for the suggestion if you find this is an important issue.

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  • SQLite doesn't have booleans or date-times.

    - by DanM
    I've been thinking about using SQLite for my next project, but I'm concerned that it seems to lack proper datetime and bit data types. If I use DbLinq (or some other ORM) to generate C# classes, will the data types of the properties be "dumbed down"? Will date-time data be placed in properties of type string or double? Will boolean data be placed in properties of type int? If yes, what are the implications? I'm envisioning a scenario where I need to write a whole second layer of classes with more specific data types and do a bunch of transformations and casts, but maybe it's not as bad as I fear. If you have any experience with this or a similar scenario, how did you handle it?

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  • Type patterns in Haskell

    - by finnsson
    I'm trying to compile a simple example of generic classes / type patterns (see http://www.haskell.org/ghc/docs/latest/html/users_guide/generic-classes.html) in Haskell but it won't compile. Any ideas about what's wrong with the code would be helpful. According to the documentation there should be a module Generics with the data types Unit, :*:, and :+: but ghc (6.12.1) complaints about Not in scope: data constructor 'Unit' etc. It seems like there's a package instant-generics with the data types :*:, :+: and U but when I import that module (instead of Generics) I get the error Illegal type pattern in the generic bindings {myPrint _ = ""} The complete source code is import Generics.Instant class MyPrint a where myPrint :: a -> String myPrint {| U |} _ = "" myPrint {| a :*: b |} (x :*: y) = "" (show x) ++ ":*:" ++ (show y) myPrint {| a :+: b |} _ = "" data Foo = Foo String instance MyPrint a => MyPrint a main = myPrint $ Foo "hi" and I compile it using ghc --make Foo.hs -fglasgow-exts -XGenerics -XUndecidableInstances P.S. The module Generics export no data types, only the functions: canDoGenerics mkGenericRhs mkTyConGenericBinds validGenericInstanceType validGenericMethodType

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  • C2664 when casting child class to templated parent class

    - by DC
    I have a parent class which is templated, and a child class which implements it. template< typename T1, typename T2> class ParentClass{ . . . }; class ChildClass : public ParentClass<MyT1, MyT2> { . . . }; And I want to have a pointer which I can use polymorphically: ParentClass<T1, T2>* ptr; ptr = static_cast<ParentClass<MyT1, MyT2>* >(new ChildClass() ); No matter how I cast it, I always get a C2664 which has the same expression: error C2664: cannot convert parameter 1 from 'ParentClass< T1,T2 *' to 'ParentClass< T1,T2 *' Is it not possible to cast pointer types between inherited types if the parent is templated, even if the types specified in the templates are the same?

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  • how to import other schema jars when using the scomp tool

    - by MikeJiang
    there is a huge amount of xml schemas for the business, some of them are common types like Money.xsd, Address.xsd, etc, while others are business specific like Customer.xsd, ShippingOrder.xsd, etc. So I decide to compile these schemas into 2 jars, one is commonbeans.jar, the other is businessbeans.jar. I've separated them into different folders. to build the commonbeans.jar is simple, just run "scomp -out commonbeans.jar ....\common*.xsd"; while run "scomp -out businessbeans.jar ....\business*.xsd" is a different story, there are errors say can't find those common types, and run "scomp -out businessbeans.jar ....\business*.xsd ....\business*.xsd" will blindly duplicate all the common types into the businessbeans.jar. so is there any way to link the commonbeans.jar when compile those busimess schemas, maybe something like "scomp -out businessbeans.jar ....\business*.xsd commonbeans.jar". I hope my poor english has expressed my issue!

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  • Best practices for handling string in VC++?

    - by Hiren Gujarati
    As I am new to Visual C++, there are so many types for handling string. When I use some type and go ahead with coding but on next step, there are in-build functions that use other types & it always require to convert one type of string to other. I found so many blogs but so confused when see so many answers & try but some are working & some are not. Please give your answer or links that gives ultimate solution for handling different types of strings in visual c++.

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  • Possibility of language data type not mapped to shipped .NET Framework?

    - by John K
    Does anybody know of a managed programming language implemented on .NET that contains a specialized data type that is not mapped through to the Common Type System/FCL/BCL or one that does not have a shipped .NET equivalent (e.g. shipped standard types like System.String, System.Int32)? This question would likely come from the perspective of someone porting a compiler (although I'm not doing that). Is it as simple as the language creating a new data type outside the BCL/FCL for its specialized type? If so does this hinder interoperability between programming languages that are otherwise accustomed to mapping all their built-in data types to what's in the BCL/FCL, like Visual Basic and C#? I can imagine this situation might come about if an obscure language compiler of some kind is ported to .NET for which there is no direct mapping of one of its implicit data types to the shipped Framework. How is this situation supported or allowed in general? What would be the expectation of the compiler and the Common Language Runtime?

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  • Dynamically adding @property in python

    - by rz
    I know that I can dynamically add an instance method to an object by doing something like: import types def my_method(self): # logic of method # ... # instance is some instance of some class instance.my_method = types.MethodType(my_method, instance) Later on I can call instance.my_method() and self will be bound correctly and everything works. Now, my question: how to do the exact same thing to obtain the behavior that decorating the new method with @property would give? I would guess something like: instance.my_method = types.MethodType(my_method, instance) instance.my_method = property(instance.my_method) But, doing that instance.my_method returns a property object.

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  • Is there a limit to the number of DataContracts that can be used by a WCF Service?

    - by Chris
    Using WCF3.5SP1, VS2008. Building a WCF service that exposes about 10 service methods. We have defined about 40 [DataContract] types that are used by the service. We now experience that adding an additional [DataContract] type to the project (in the same namespace as the other existing types) does not get properly exposed. The new type is not in the XSD schemas generated with the WSDL. We have gone so far as to copy and rename an existing (and working) type, but it too is not present in the generated WSDL/XSD. We've tried this on two different developer machines, same problem. Is there a limit to the number of types that can exposed as [DataContract] for a Service? per Namespace?

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  • Best practices about creating a generic object dictionary in C#? Is this bad?

    - by JimDaniel
    For clarity I am using C# 3.5/Asp.Net MVC 2 Here is what I have done: I wanted the ability to add/remove functionality to an object at run-time. So I simply added a generic object dictionary to my class like this: public Dictionary<int, object> Components { get; set; } Then I can add/remove any kind of .Net object into this dictionary at run-time. To insert an object I do something like this: var tag = new Tag(); myObject.Components.Add((int)Types.Components.Tag, tag); Then to retrieve I just do this: if(myObject.Components.ContainsKey((int)Types.Components.Tag)) { var tag = myObject.Components[(int)Types.Components.Tag] as Tag; if(tag != null) { //do stuff } } Somehow I feel sneaky doing this. It works okay, but I am wondering what you guys think about it as a best practice. Thanks for your input, Daniel

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  • Creating dynamic generics at runtime using Reflection

    - by MPhlegmatic
    I'm trying to convert a Dictionary< dynamic, dynamic to a statically-typed one by examining the types of the keys and values and creating a new Dictionary of the appropriate types using Reflection. If I know the key and value types, I can do the following: Type dictType = typeof(Dictionary<,>); newDict = Activator.CreateInstance(dictType.MakeGenericType(new Type[] { keyType, valueType })); However, I may need to create, for example, a Dictionary< MyKeyType, dynamic if the values are not all of the same type, and I can't figure out how to specify the dynamic type, since typeof(dynamic) isn't viable. How would I go about doing this, and/or is there a simpler way to accomplish what I'm trying to do?

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  • What is a common name for inheritance, composition, aggregation, delegation?

    - by Eye of Hell
    Hello. After program is separated into small object, these objects must be connected with each over. Where are different types of connection. Inheritance, composition, aggregation, delegation. These types has many kinds and patterns like loose coupling, tight coupling, inversion of control, delegation via interfaces etc. What is a correct common name for mentioned types of connections? I can suggest that they all are called 'coupling', but i can't find any good classification in google, so maybe i'm trying to use a wrong term? Maybe anyone knows a solid, trusted classification that i can user for terminology?

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  • C#: Oracle Data Type Equivalence with OracleDbType

    - by Partial
    Situation: I am creating an app in C# that uses Oracle.DataAccess.Client (11g) to do certain operations on a Oracle database with stored procedures. I am aware that there is a certain enum (OracleDbType) that contains the Oracle data types, but I am not sure which one to use for certain types. Questions: What is the equivalent Oracle PL/SQL data type for each enumerated type in the OracleDbType enumeration? There are three types of integer (Int16, Int32, Int64) in the OracleDbType... how to know which one to use or are they all suppose to work?

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  • Django - User account with multiple identities

    - by Scott Willman
    Synopsis: Each User account has a UserProfile to hold extended info like phone numbers, addresses, etc. Then, a User account can have multiple Identities. There are multiple types of identities that hold different types of information. The structure would be like so: User |<-FK- UserProfile | |<-FK- IdentityType1 |<-FK- IdentityType1 |<-FK- IdentityType2 |<-FK- IdentityType3 (current) |<-FK- IdentityType3 |<-FK- IdentityType3 The User account can be connected to n number of Identities of different types but can only use one Identity at a time. Seemingly, the Django way would be to collect all of the connected identities (user.IdentityType1_set.select_related()) into a QuerySet and then check each one for some kind of 'current' field. Question: Can anyone think of a better way to select the 'current' marked Identity than doing three DB queries (one for each IdentityType)?

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  • How to reliably specialize template with intptr_t in 32 and 64 bit environments?

    - by vava
    I have a template I want to specialize with two int types, one of them plain old int and another one is intptr_t. On 64 bit platform they have different sizes and I can do that with ease but on 32 bit both types are the same and compiler throws an error about redefinition. What can I do to fix it except for disabling one of definitions off with preprocessor? Some code as an example: template<typename T> type * convert(); template<> type * convert<int>() { return getProperIntType(sizeof(int)); } template<> type * convert<intptr_t>() { return getProperIntType(sizeof(intptr_t)); } //this template can be specialized with non-integral types as well, // so I can't just use sizeof() as template parameter. template<> type * convert<void>() { return getProperVoidType(); }

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  • Is there any way to retrieve a float from a varargs function's parameters?

    - by Jared P
    If the function was defined with a prototype which explicitly stated the types of the parameters, eg. void somefunc(int arg1, float arg2); but is implemented as void somefunc(int arg1, ...) { ... } is it possible to use va_arg to retrieve a float? It's normally prevented from doing this because varargs functions have implicit type promotions, like float to double, so trying to retrieve an unpromoted type is unsupported, even though the function is being called with the unpromoted type do to the more specific function prototype. The reason for this is to retrieve arguments of different types at runtime, as part of an obj-c interpreter, where one function will be reused for all different types of methods. This would be best as architecture independent (so that if nothing else the same code works on simulator and on device), although if there is no way to do this then device specific fixes will be accepted.

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  • Cross-referencing UML models in VS 2010

    - by cheaster
    I am just starting to explore/use the UML modeling support in Visual Studio 2010 Umltimate. I have created two model projects within a single solution. Let's call them Model A and Model B. I have some data types (classes) defined in Model B. I want to use them as return types for operations in Model A. However, I cannot figure out how to make the types defined in Model B show up in Model A when attempting to set return type on an operation. Any help/suggestions would be greatly appreciated! Thanks!

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  • powershell folder stats

    - by huppy_doodoo
    Hi all, I keep all modules of our system in one dir (e.g. All\ModuleA; All\ModuleB). I want to see what types of files are most numerous and take up the most space, by module. So, I'd like output along the lines of: ModName,java-count,java-size,xml-count,xml-size,png-count,png-size... ModuleA,30,0.2,100,2.3,0,0,... ModuleB,21,0.1,20,0.7,1,1.2 Not all modules have files of all types, so this will only work if I list all types for all module (with lots of zeros). I have something that almost works, but it's hideous, verbose and inefficient. I'm sure someone can help me see the light :-) (which, by the way, can be a piece of freeware software that does this out of the box; I only chose to do this in powershell out of interest). thanks

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  • Persisting Serializable Objects in Hibernate

    - by VeeArr
    I am attempting to persist objects that contain some large Serializable types. I want Hibernate to automatically generate my DDL (using Hibernate annotations). For the most part, this works, but the default database column type used by Hibernate when persisting these types is tinyblob. Unfortunately, this causes crashes when attempting to persist my class, because these types will not fit within the length of tinyblob. However, if I manually set the type (using @Column(columnDefinition="longblob")), it works fine. Is there any way to make the default binary type longblob instead of tinyblob, so that I don't need to manually specify the @Column annotation on each field?

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  • Creating packages in code – Execute SQL Task

    The Execute SQL Task is for obvious reasons very well used, so I thought if you are building packages in code the chances are you will be using it. Using the task basic features of the task are quite straightforward, add the task and set some properties, just like any other. When you start interacting with variables though it can be a little harder to grasp so these samples should see you through. Some of these more advanced features are explained in much more detail in our ever popular post The Execute SQL Task, here I’ll just be showing you how to implement them in code. The abbreviated code blocks below demonstrate the different features of the task. The complete code has been encapsulated into a sample class which you can download (ExecSqlPackage.cs). Each feature described has its own method in the sample class which is mentioned after the code block. This first sample just shows adding the task, setting the basic properties for a connection and of course an SQL statement. Package package = new Package(); // Add the SQL OLE-DB connection ConnectionManager sqlConnection = AddSqlConnection(package, "localhost", "master"); // Add the SQL Task package.Executables.Add("STOCK:SQLTask"); // Get the task host wrapper TaskHost taskHost = package.Executables[0] as TaskHost; // Set required properties taskHost.Properties["Connection"].SetValue(taskHost, sqlConnection.ID); taskHost.Properties["SqlStatementSource"].SetValue(taskHost, "SELECT * FROM sysobjects"); For the full version of this code, see the CreatePackage method in the sample class. The AddSqlConnection method is a helper method that adds an OLE-DB connection to the package, it is of course in the sample class file too. Returning a single value with a Result Set The following sample takes a different approach, getting a reference to the ExecuteSQLTask object task itself, rather than just using the non-specific TaskHost as above. Whilst it means we need to add an extra reference to our project (Microsoft.SqlServer.SQLTask) it makes coding much easier as we have compile time validation of any property and types we use. For the more complex properties that is very valuable and saves a lot of time during development. The query has also been changed to return a single value, one row and one column. The sample shows how we can return that value into a variable, which we also add to our package in the code. To do this manually you would set the Result Set property on the General page to Single Row and map the variable on the Result Set page in the editor. Package package = new Package(); // Add the SQL OLE-DB connection ConnectionManager sqlConnection = AddSqlConnection(package, "localhost", "master"); // Add the SQL Task package.Executables.Add("STOCK:SQLTask"); // Get the task host wrapper TaskHost taskHost = package.Executables[0] as TaskHost; // Add variable to hold result value package.Variables.Add("Variable", false, "User", 0); // Get the task object ExecuteSQLTask task = taskHost.InnerObject as ExecuteSQLTask; // Set core properties task.Connection = sqlConnection.Name; task.SqlStatementSource = "SELECT id FROM sysobjects WHERE name = 'sysrowsets'"; // Set single row result set task.ResultSetType = ResultSetType.ResultSetType_SingleRow; // Add result set binding, map the id column to variable task.ResultSetBindings.Add(); IDTSResultBinding resultBinding = task.ResultSetBindings.GetBinding(0); resultBinding.ResultName = "id"; resultBinding.DtsVariableName = "User::Variable"; For the full version of this code, see the CreatePackageResultVariable method in the sample class. The other types of Result Set behaviour are just a variation on this theme, set the property and map the result binding as required. Parameter Mapping for SQL Statements This final example uses a parameterised SQL statement, with the coming from a variable. The syntax varies slightly between connection types, as explained in the Working with Parameters and Return Codes in the Execute SQL Taskhelp topic, but OLE-DB is the most commonly used, for which a question mark is the parameter value placeholder. Package package = new Package(); // Add the SQL OLE-DB connection ConnectionManager sqlConnection = AddSqlConnection(package, ".", "master"); // Add the SQL Task package.Executables.Add("STOCK:SQLTask"); // Get the task host wrapper TaskHost taskHost = package.Executables[0] as TaskHost; // Get the task object ExecuteSQLTask task = taskHost.InnerObject as ExecuteSQLTask; // Set core properties task.Connection = sqlConnection.Name; task.SqlStatementSource = "SELECT id FROM sysobjects WHERE name = ?"; // Add variable to hold parameter value package.Variables.Add("Variable", false, "User", "sysrowsets"); // Add input parameter binding task.ParameterBindings.Add(); IDTSParameterBinding parameterBinding = task.ParameterBindings.GetBinding(0); parameterBinding.DtsVariableName = "User::Variable"; parameterBinding.ParameterDirection = ParameterDirections.Input; parameterBinding.DataType = (int)OleDBDataTypes.VARCHAR; parameterBinding.ParameterName = "0"; parameterBinding.ParameterSize = 255; For the full version of this code, see the CreatePackageParameterVariable method in the sample class. You’ll notice the data type has to be specified for the parameter IDTSParameterBinding .DataType Property, and these type codes are connection specific too. My enumeration I wrote several years ago is shown below was probably done by reverse engineering a package and also the API header file, but I recently found a very handy post that covers more connections as well for exactly this, Setting the DataType of IDTSParameterBinding objects (Execute SQL Task). /// <summary> /// Enumeration of OLE-DB types, used when mapping OLE-DB parameters. /// </summary> private enum OleDBDataTypes { BYTE = 0x11, CURRENCY = 6, DATE = 7, DB_VARNUMERIC = 0x8b, DBDATE = 0x85, DBTIME = 0x86, DBTIMESTAMP = 0x87, DECIMAL = 14, DOUBLE = 5, FILETIME = 0x40, FLOAT = 4, GUID = 0x48, LARGE_INTEGER = 20, LONG = 3, NULL = 1, NUMERIC = 0x83, NVARCHAR = 130, SHORT = 2, SIGNEDCHAR = 0x10, ULARGE_INTEGER = 0x15, ULONG = 0x13, USHORT = 0x12, VARCHAR = 0x81, VARIANT_BOOL = 11 } Download Sample code ExecSqlPackage.cs (10KB)

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  • Creating packages in code – Execute SQL Task

    The Execute SQL Task is for obvious reasons very well used, so I thought if you are building packages in code the chances are you will be using it. Using the task basic features of the task are quite straightforward, add the task and set some properties, just like any other. When you start interacting with variables though it can be a little harder to grasp so these samples should see you through. Some of these more advanced features are explained in much more detail in our ever popular post The Execute SQL Task, here I’ll just be showing you how to implement them in code. The abbreviated code blocks below demonstrate the different features of the task. The complete code has been encapsulated into a sample class which you can download (ExecSqlPackage.cs). Each feature described has its own method in the sample class which is mentioned after the code block. This first sample just shows adding the task, setting the basic properties for a connection and of course an SQL statement. Package package = new Package(); // Add the SQL OLE-DB connection ConnectionManager sqlConnection = AddSqlConnection(package, "localhost", "master"); // Add the SQL Task package.Executables.Add("STOCK:SQLTask"); // Get the task host wrapper TaskHost taskHost = package.Executables[0] as TaskHost; // Set required properties taskHost.Properties["Connection"].SetValue(taskHost, sqlConnection.ID); taskHost.Properties["SqlStatementSource"].SetValue(taskHost, "SELECT * FROM sysobjects"); For the full version of this code, see the CreatePackage method in the sample class. The AddSqlConnection method is a helper method that adds an OLE-DB connection to the package, it is of course in the sample class file too. Returning a single value with a Result Set The following sample takes a different approach, getting a reference to the ExecuteSQLTask object task itself, rather than just using the non-specific TaskHost as above. Whilst it means we need to add an extra reference to our project (Microsoft.SqlServer.SQLTask) it makes coding much easier as we have compile time validation of any property and types we use. For the more complex properties that is very valuable and saves a lot of time during development. The query has also been changed to return a single value, one row and one column. The sample shows how we can return that value into a variable, which we also add to our package in the code. To do this manually you would set the Result Set property on the General page to Single Row and map the variable on the Result Set page in the editor. Package package = new Package(); // Add the SQL OLE-DB connection ConnectionManager sqlConnection = AddSqlConnection(package, "localhost", "master"); // Add the SQL Task package.Executables.Add("STOCK:SQLTask"); // Get the task host wrapper TaskHost taskHost = package.Executables[0] as TaskHost; // Add variable to hold result value package.Variables.Add("Variable", false, "User", 0); // Get the task object ExecuteSQLTask task = taskHost.InnerObject as ExecuteSQLTask; // Set core properties task.Connection = sqlConnection.Name; task.SqlStatementSource = "SELECT id FROM sysobjects WHERE name = 'sysrowsets'"; // Set single row result set task.ResultSetType = ResultSetType.ResultSetType_SingleRow; // Add result set binding, map the id column to variable task.ResultSetBindings.Add(); IDTSResultBinding resultBinding = task.ResultSetBindings.GetBinding(0); resultBinding.ResultName = "id"; resultBinding.DtsVariableName = "User::Variable"; For the full version of this code, see the CreatePackageResultVariable method in the sample class. The other types of Result Set behaviour are just a variation on this theme, set the property and map the result binding as required. Parameter Mapping for SQL Statements This final example uses a parameterised SQL statement, with the coming from a variable. The syntax varies slightly between connection types, as explained in the Working with Parameters and Return Codes in the Execute SQL Taskhelp topic, but OLE-DB is the most commonly used, for which a question mark is the parameter value placeholder. Package package = new Package(); // Add the SQL OLE-DB connection ConnectionManager sqlConnection = AddSqlConnection(package, ".", "master"); // Add the SQL Task package.Executables.Add("STOCK:SQLTask"); // Get the task host wrapper TaskHost taskHost = package.Executables[0] as TaskHost; // Get the task object ExecuteSQLTask task = taskHost.InnerObject as ExecuteSQLTask; // Set core properties task.Connection = sqlConnection.Name; task.SqlStatementSource = "SELECT id FROM sysobjects WHERE name = ?"; // Add variable to hold parameter value package.Variables.Add("Variable", false, "User", "sysrowsets"); // Add input parameter binding task.ParameterBindings.Add(); IDTSParameterBinding parameterBinding = task.ParameterBindings.GetBinding(0); parameterBinding.DtsVariableName = "User::Variable"; parameterBinding.ParameterDirection = ParameterDirections.Input; parameterBinding.DataType = (int)OleDBDataTypes.VARCHAR; parameterBinding.ParameterName = "0"; parameterBinding.ParameterSize = 255; For the full version of this code, see the CreatePackageParameterVariable method in the sample class. You’ll notice the data type has to be specified for the parameter IDTSParameterBinding .DataType Property, and these type codes are connection specific too. My enumeration I wrote several years ago is shown below was probably done by reverse engineering a package and also the API header file, but I recently found a very handy post that covers more connections as well for exactly this, Setting the DataType of IDTSParameterBinding objects (Execute SQL Task). /// <summary> /// Enumeration of OLE-DB types, used when mapping OLE-DB parameters. /// </summary> private enum OleDBDataTypes { BYTE = 0x11, CURRENCY = 6, DATE = 7, DB_VARNUMERIC = 0x8b, DBDATE = 0x85, DBTIME = 0x86, DBTIMESTAMP = 0x87, DECIMAL = 14, DOUBLE = 5, FILETIME = 0x40, FLOAT = 4, GUID = 0x48, LARGE_INTEGER = 20, LONG = 3, NULL = 1, NUMERIC = 0x83, NVARCHAR = 130, SHORT = 2, SIGNEDCHAR = 0x10, ULARGE_INTEGER = 0x15, ULONG = 0x13, USHORT = 0x12, VARCHAR = 0x81, VARIANT_BOOL = 11 } Download Sample code ExecSqlPackage.cs (10KB)

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  • MySQL Syslog Audit Plugin

    - by jonathonc
    This post shows the construction process of the Syslog Audit plugin that was presented at MySQL Connect 2012. It is based on an environment that has the appropriate development tools enabled including gcc,g++ and cmake. It also assumes you have downloaded the MySQL source code (5.5.16 or higher) and have compiled and installed the system into the /usr/local/mysql directory ready for use.  The information provided below is designed to show the different components that make up a plugin, and specifically an audit type plugin, and how it comes together to be used within the MySQL service. The MySQL Reference Manual contains information regarding the plugin API and how it can be used, so please refer there for more detailed information. The code in this post is designed to give the simplest information necessary, so handling every return code, managing race conditions etc is not part of this example code. Let's start by looking at the most basic implementation of our plugin code as seen below: /*    Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.    Author:  Jonathon Coombes    Licence: GPL    Description: An auditing plugin that logs to syslog and                 can adjust the loglevel via the system variables. */ #include <stdio.h> #include <string.h> #include <mysql/plugin_audit.h> #include <syslog.h> There is a commented header detailing copyright/licencing and meta-data information and then the include headers. The two important include statements for our plugin are the syslog.h plugin, which gives us the structures for syslog, and the plugin_audit.h include which has details regarding the audit specific plugin api. Note that we do not need to include the general plugin header plugin.h, as this is done within the plugin_audit.h file already. To implement our plugin within the current implementation we need to add it into our source code and compile. > cd /usr/local/src/mysql-5.5.28/plugin > mkdir audit_syslog > cd audit_syslog A simple CMakeLists.txt file is created to manage the plugin compilation: MYSQL_ADD_PLUGIN(audit_syslog audit_syslog.cc MODULE_ONLY) Run the cmake  command at the top level of the source and then you can compile the plugin using the 'make' command. This results in a compiled audit_syslog.so library, but currently it is not much use to MySQL as there is no level of api defined to communicate with the MySQL service. Now we need to define the general plugin structure that enables MySQL to recognise the library as a plugin and be able to install/uninstall it and have it show up in the system. The structure is defined in the plugin.h file in the MySQL source code.  /*   Plugin library descriptor */ mysql_declare_plugin(audit_syslog) {   MYSQL_AUDIT_PLUGIN,           /* plugin type                    */   &audit_syslog_descriptor,     /* descriptor handle               */   "audit_syslog",               /* plugin name                     */   "Author Name",                /* author                          */   "Simple Syslog Audit",        /* description                     */   PLUGIN_LICENSE_GPL,           /* licence                         */   audit_syslog_init,            /* init function     */   audit_syslog_deinit,          /* deinit function */   0x0001,                       /* plugin version                  */   NULL,                         /* status variables        */   NULL,                         /* system variables                */   NULL,                         /* no reserves                     */   0,                            /* no flags                        */ } mysql_declare_plugin_end; The general plugin descriptor above is standard for all plugin types in MySQL. The plugin type is defined along with the init/deinit functions and interface methods into the system for sharing information, and various other metadata information. The descriptors have an internally recognised version number so that plugins can be matched against the api on the running server. The other details are usually related to the type-specific methods and structures to implement the plugin. Each plugin has a type-specific descriptor as well which details how the plugin is implemented for the specific purpose of that plugin type. /*   Plugin type-specific descriptor */ static struct st_mysql_audit audit_syslog_descriptor= {   MYSQL_AUDIT_INTERFACE_VERSION,                        /* interface version    */   NULL,                                                 /* release_thd function */   audit_syslog_notify,                                  /* notify function      */   { (unsigned long) MYSQL_AUDIT_GENERAL_CLASSMASK |                     MYSQL_AUDIT_CONNECTION_CLASSMASK }  /* class mask           */ }; In this particular case, the release_thd function has not been defined as it is not required. The important method for auditing is the notify function which is activated when an event occurs on the system. The notify function is designed to activate on an event and the implementation will determine how it is handled. For the audit_syslog plugin, the use of the syslog feature sends all events to the syslog for recording. The class mask allows us to determine what type of events are being seen by the notify function. There are currently two major types of event: 1. General Events: This includes general logging, errors, status and result type events. This is the main one for tracking the queries and operations on the database. 2. Connection Events: This group is based around user logins. It monitors connections and disconnections, but also if somebody changes user while connected. With most audit plugins, the principle behind the plugin is to track changes to the system over time and counters can be an important part of this process. The next step is to define and initialise the counters that are used to track the events in the service. There are 3 counters defined in total for our plugin - the # of general events, the # of connection events and the total number of events.  static volatile int total_number_of_calls; /* Count MYSQL_AUDIT_GENERAL_CLASS event instances */ static volatile int number_of_calls_general; /* Count MYSQL_AUDIT_CONNECTION_CLASS event instances */ static volatile int number_of_calls_connection; The init and deinit functions for the plugin are there to be called when the plugin is activated and when it is terminated. These offer the best option to initialise the counters for our plugin: /*  Initialize the plugin at server start or plugin installation. */ static int audit_syslog_init(void *arg __attribute__((unused))) {     openlog("mysql_audit:",LOG_PID|LOG_PERROR|LOG_CONS,LOG_USER);     total_number_of_calls= 0;     number_of_calls_general= 0;     number_of_calls_connection= 0;     return(0); } The init function does a call to openlog to initialise the syslog functionality. The parameters are the service to log under ("mysql_audit" in this case), the syslog flags and the facility for the logging. Then each of the counters are initialised to zero and a success is returned. If the init function is not defined, it will return success by default. /*  Terminate the plugin at server shutdown or plugin deinstallation. */ static int audit_syslog_deinit(void *arg __attribute__((unused))) {     closelog();     return(0); } The deinit function will simply close our syslog connection and return success. Note that the syslog functionality is part of the glibc libraries and does not require any external factors.  The function names are what we define in the general plugin structure, so these have to match otherwise there will be errors. The next step is to implement the event notifier function that was defined in the type specific descriptor (audit_syslog_descriptor) which is audit_syslog_notify. /* Event notifier function */ static void audit_syslog_notify(MYSQL_THD thd __attribute__((unused)), unsigned int event_class, const void *event) { total_number_of_calls++; if (event_class == MYSQL_AUDIT_GENERAL_CLASS) { const struct mysql_event_general *event_general= (const struct mysql_event_general *) event; number_of_calls_general++; syslog(audit_loglevel,"%lu: User: %s Command: %s Query: %s\n", event_general->general_thread_id, event_general->general_user, event_general->general_command, event_general->general_query ); } else if (event_class == MYSQL_AUDIT_CONNECTION_CLASS) { const struct mysql_event_connection *event_connection= (const struct mysql_event_connection *) event; number_of_calls_connection++; syslog(audit_loglevel,"%lu: User: %s@%s[%s] Event: %d Status: %d\n", event_connection->thread_id, event_connection->user, event_connection->host, event_connection->ip, event_connection->event_subclass, event_connection->status ); } }   In the case of an event, the notifier function is called. The first step is to increment the total number of events that have occurred in our database.The event argument is then cast into the appropriate event structure depending on the class type, of general event or connection event. The event type counters are incremented and details are sent via the syslog() function out to the system log. There are going to be different line formats and information returned since the general events have different data compared to the connection events, even though some of the details overlap, for example, user, thread id, host etc. On compiling the code now, there should be no errors and the resulting audit_syslog.so can be loaded into the server and ready to use. Log into the server and type: mysql> INSTALL PLUGIN audit_syslog SONAME 'audit_syslog.so'; This will install the plugin and will start updating the syslog immediately. Note that the audit plugin attaches to the immediate thread and cannot be uninstalled while that thread is active. This means that you cannot run the UNISTALL command until you log into a different connection (thread) on the server. Once the plugin is loaded, the system log will show output such as the following: Oct  8 15:33:21 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: (null)  Query: INSTALL PLUGIN audit_syslog SONAME 'audit_syslog.so' Oct  8 15:33:21 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: Query  Query: INSTALL PLUGIN audit_syslog SONAME 'audit_syslog.so' Oct  8 15:33:40 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: (null)  Query: show tables Oct  8 15:33:40 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: Query  Query: show tables Oct  8 15:33:43 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: (null)  Query: select * from t1 Oct  8 15:33:43 machine mysql_audit:[8337]: 87: User: root[root] @ localhost []  Command: Query  Query: select * from t1 It appears that two of each event is being shown, but in actuality, these are two separate event types - the result event and the status event. This could be refined further by changing the audit_syslog_notify function to handle the different event sub-types in a different manner.  So far, it seems that the logging is working with events showing up in the syslog output. The issue now is that the counters created earlier to track the number of events by type are not accessible when the plugin is being run. Instead there needs to be a way to expose the plugin specific information to the service and vice versa. This could be done via the information_schema plugin api, but for something as simple as counters, the obvious choice is the system status variables. This is done using the standard structure and the declaration: /*  Plugin status variables for SHOW STATUS */ static struct st_mysql_show_var audit_syslog_status[]= {   { "Audit_syslog_total_calls",     (char *) &total_number_of_calls,     SHOW_INT },   { "Audit_syslog_general_events",     (char *) &number_of_calls_general,     SHOW_INT },   { "Audit_syslog_connection_events",     (char *) &number_of_calls_connection,     SHOW_INT },   { 0, 0, SHOW_INT } };   The structure is simply the name that will be displaying in the mysql service, the address of the associated variables, and the data type being used for the counter. It is finished with a blank structure to show that there are no more variables. Remember that status variables may have the same name for variables from other plugin, so it is considered appropriate to add the plugin name at the start of the status variable name to avoid confusion. Looking at the status variables in the mysql client shows something like the following: mysql> show global status like "audit%"; +--------------------------------+-------+ | Variable_name                  | Value | +--------------------------------+-------+ | Audit_syslog_connection_events | 1     | | Audit_syslog_general_events    | 2     | | Audit_syslog_total_calls       | 3     | +--------------------------------+-------+ 3 rows in set (0.00 sec) The final connectivity piece for the plugin is to allow the interactive change of the logging level between the plugin and the system. This requires the ability to send changes via the mysql service through to the plugin. This is done using the system variables interface and defining a single variable to keep track of the active logging level for the facility. /* Plugin system variables for SHOW VARIABLES */ static MYSQL_SYSVAR_STR(loglevel, audit_loglevel,                         PLUGIN_VAR_RQCMDARG,                         "User can specify the log level for auditing",                         audit_loglevel_check, audit_loglevel_update, "LOG_NOTICE"); static struct st_mysql_sys_var* audit_syslog_sysvars[] = {     MYSQL_SYSVAR(loglevel),     NULL }; So now the system variable 'loglevel' is defined for the plugin and associated to the global variable 'audit_loglevel'. The check or validation function is defined to make sure that no garbage values are attempted in the update of the variable. The update function is used to save the new value to the variable. Note that the audit_syslog_sysvars structure is defined in the general plugin descriptor to associate the link between the plugin and the system and how much they interact. Next comes the implementation of the validation function and the update function for the system variable. It is worth noting that if you have a simple numeric such as integers for the variable types, the validate function is often not required as MySQL will handle the automatic check and validation of simple types. /* longest valid value */ #define MAX_LOGLEVEL_SIZE 100 /* hold the valid values */ static const char *possible_modes[]= { "LOG_ERROR", "LOG_WARNING", "LOG_NOTICE", NULL };  static int audit_loglevel_check(     THD*                        thd,    /*!< in: thread handle */     struct st_mysql_sys_var*    var,    /*!< in: pointer to system                                         variable */     void*                       save,   /*!< out: immediate result                                         for update function */     struct st_mysql_value*      value)  /*!< in: incoming string */ {     char buff[MAX_LOGLEVEL_SIZE];     const char *str;     const char **found;     int length;     length= sizeof(buff);     if (!(str= value->val_str(value, buff, &length)))         return 1;     /*         We need to return a pointer to a locally allocated value in "save".         Here we pick to search for the supplied value in an global array of         constant strings and return a pointer to one of them.         The other possiblity is to use the thd_alloc() function to allocate         a thread local buffer instead of the global constants.     */     for (found= possible_modes; *found; found++)     {         if (!strcmp(*found, str))         {             *(const char**)save= *found;             return 0;         }     }     return 1; } The validation function is simply to take the value being passed in via the SET GLOBAL VARIABLE command and check if it is one of the pre-defined values allowed  in our possible_values array. If it is found to be valid, then the value is assigned to the save variable ready for passing through to the update function. static void audit_loglevel_update(     THD*                        thd,        /*!< in: thread handle */     struct st_mysql_sys_var*    var,        /*!< in: system variable                                             being altered */     void*                       var_ptr,    /*!< out: pointer to                                             dynamic variable */     const void*                 save)       /*!< in: pointer to                                             temporary storage */ {     /* assign the new value so that the server can read it */     *(char **) var_ptr= *(char **) save;     /* assign the new value to the internal variable */     audit_loglevel= *(char **) save; } Since all the validation has been done already, the update function is quite simple for this plugin. The first part is to update the system variable pointer so that the server can read the value. The second part is to update our own global plugin variable for tracking the value. Notice that the save variable is passed in as a void type to allow handling of various data types, so it must be cast to the appropriate data type when assigning it to the variables. Looking at how the latest changes affect the usage of the plugin and the interaction within the server shows: mysql> show global variables like "audit%"; +-----------------------+------------+ | Variable_name         | Value      | +-----------------------+------------+ | audit_syslog_loglevel | LOG_NOTICE | +-----------------------+------------+ 1 row in set (0.00 sec) mysql> set global audit_syslog_loglevel="LOG_ERROR"; Query OK, 0 rows affected (0.00 sec) mysql> show global status like "audit%"; +--------------------------------+-------+ | Variable_name                  | Value | +--------------------------------+-------+ | Audit_syslog_connection_events | 1     | | Audit_syslog_general_events    | 11    | | Audit_syslog_total_calls       | 12    | +--------------------------------+-------+ 3 rows in set (0.00 sec) mysql> show global variables like "audit%"; +-----------------------+-----------+ | Variable_name         | Value     | +-----------------------+-----------+ | audit_syslog_loglevel | LOG_ERROR | +-----------------------+-----------+ 1 row in set (0.00 sec)   So now we have a plugin that will audit the events on the system and log the details to the system log. It allows for interaction to see the number of different events within the server details and provides a mechanism to change the logging level interactively via the standard system methods of the SET command. A more complex auditing plugin may have more detailed code, but each of the above areas is what will be involved and simply expanded on to add more functionality. With the above skeleton code, it is now possible to create your own audit plugins to implement your own auditing requirements. If, however, you are not of the coding persuasion, then you could always consider the option of the MySQL Enterprise Audit plugin that is available to purchase.

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