.net - System.Data.SqlTypes Classes?
Jan 20, 2012
Since most of the projects I work on are exclusively SQL Server 2005/2008 database driver, I was wondering about the implications of using System.Data.SqlTypes classes as data types in my VB.Net Framework 4.0 code.For example currently I define integer variables as Dim X as Integer.Using System.Data.SqlType classes I would define my intege variables as.Dim X as System.Data.SqlTypes.SqlInt32 implications for performance, serialization and databinding. One difference would be that all variables would default to Null.
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Jun 22, 2010
I can't get past this error in my loop through the data reader specifically dr(12). I tried adding .To String but that doesn't seem to work either. Can someone help me with what need to do so it can read even if there is a Null value. My code is below:
While objDataReader.Read()
'Set up DataRow object
Dim dr As DataRow = DataReaderTable.NewRow
[code].....
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May 26, 2010
It looks like they are converted to regular date types in the generated proxy object.I'd like to optionally pass null values for these dates.Other than switching to WCF (no time to learn it right now), what is the best way to handle this situation. It looks like I also cannot pass NULLABLE date types.
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Jun 6, 2011
I have an InvalidCastException Error in my program. The program is that i try to insert an employee record into a database table after getting the details from a form. I've used Money data type is SQL Server for salary and SqlTypes.SqlDecimal data type in employee template class. i've used a stored procedure to pass the values and i add the basic value by passing a parameter by the method
Dim prm8 As SqlParameter = com.Parameters.Add("@basic", SqlDbType.Money)
prm8.Direction = ParameterDirection.Input
prm8.Value = emp.Bsc
I've used the money datatype itself even in the stored procedure variable.I get the following error.
failed to convert parameter value from sql decimal to decimal
Even if i use
prm8.Value = Convert.ToDecimal(emp.Bsc)
I get an error Unable to cast object of type 'System.Data.SqlTypes.SqlDecimal' to type 'System.IConvertible'.
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Mar 9, 2009
I would like to utilize classes that inherit the System.Data name space.Specifically, I would like to have classes CarColumn, CarTable, and CarSet derived from DataColumn, DataTable, and Dataset respectively.I would like to be able to add additional properities to each class. As an example this is how I would like to reference items within the classes:
CarSet.CarTable(0).Columns(0).foo
CarSet.CarTable(0).bar
I know that VB.Net is not capable of Multi-Inheritance.
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Feb 29, 2012
I remember seeing somewhere on the net that there are classes in .Net that will return information about your computer. I know that System.Environment returns some of this information like MachineName and some other stuff. Are there other classes that will return information such as hard drive size, free and used space, total memory, used memory?
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Nov 17, 2009
I need to generate a class at runtime similar to System.Resources where you can add a resource eg 'picture.bmp' and it immediatelly is accessible as 'System.Resources.picture.bmp'. I presume I need to generate XLM or/and XLSD at design time and then deserialise at runtime but I cant find a reference on how to do this. Specially without knowing the generic class in advance (as 'System.Resources' doesnt know all the resources in advance).
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Jul 31, 2009
I am fresher in vb.net but I want to develop a project in this case I want to use the system.Configuration namespace's specific calsses. But I am not clear which class i use and why it's function and it's use.
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Sep 2, 2011
I've spent a substantial amount of time trying to figure this out, but I keep getting the same error
A first chance exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll
A first chance exception of type 'System.NullReferenceException' occurred in project1.exe
This happens when I try to use the DataReader.my code is
Public Function Identification() As List(Of Integer)
Dim returnIndex As New List(Of Integer)
Dim dbCount As String = "SELECT Bookingid FROM bookdetail WHERE Date =" & getCurrentTimeString() & " 12:00:00 a.m."
Dim count As Integer = 0
[code]....
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Aug 28, 2009
I have been developing some components for our products at work, and one of them is based off the flow layout panel.What i would like to do is provide a custom designer for it, but without loosing the features provided by it's default designer (System.Windows.Forms.Design.FlowLayoutPanelDesigner) which is marked as internal.Using Reflector i thought i would just implement it again myself, seeing as it inherits from 'FlowPanelDesigner and that from PanelDesigner` all of which are internal.
Why would these classes be specifically marked as internal? Is it due to them being specifically for Visual Studio use, and thus not 'framework' code?Also, is there an easier option that re-implementing all the functionality?
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Feb 28, 2010
My software handles multiple operations on files, and I have now finished writing the related functions, using the System.IO classes. I now need to add support for network drives. Using a mapping works very well (although Directory.GetFiles is a bit low, and I don't know why), but I'd now like to be able to deal directly with paths such as \192.168.0.10Shared FolderMyDrive. Is there any way to handle this type of paths other than mounting the drive to an available drive letter, using the newly generated path, and then unmounting?
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May 5, 2010
Exists a good tutorial or example that shows how to use these classes from namespace System.Drawing.Imaging.
My idea is, to produce Bitmaps and to compress them. I don't know if for my case IO Streaming is important because I don't want to save the bitmap on my hard disk.
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Sep 4, 2011
i need to clear this error
A first chance exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll
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Jan 22, 2009
I am just trying to get the system to open a database and I get this error:
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
here's the entire code of the main form
=======================================
Imports System
Imports System.Data
Imports System.Data.SqlClient
[code]....
the error is generated at the open method note* this same code works fine in another computer, the main difference is that this one has a 64 bit OS.
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Jan 26, 2009
i am trying to connect to an MS Access database and I am getting an erro message on the following line of
searchtable_command = New SqlClient.SqlCommand(searchtable_string, testsearch_connection)
Error:'System.Data.Odbc.OdbcConnection' cannot be converted to 'System.Data.SqlClient.SqlConnection'.
Here my connection string:
Dim testsearch_connection As New Odbc.OdbcConnection("Provider=MSDASQL;Driver={Microsoft Access Driver (*.mdb)};Dbq=C:CesarAccessdatabase.mdb;Uid=admin;Pwd=;")
What am I missing?
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Jul 9, 2010
I Have just been watching a video on throwing Exceptions. Are you supposed to throw System.Exceptions from within your custom classes. to the calling code, Which other way can they communicate. I have read in several places it is bad practice to throw SystemExeptions.
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Jul 7, 2010
For my applications I use the following class:
Imports System.Security.Cryptography
Imports System.IO
Imports System.Text
'SymmCrypto is a wrapper of System.Security.Cryptography.SymmetricAlgorithm
[code]....
Most of the time this works as it should, but sometimes it encodes a string and the gives an error on decoding it. The error message is: Invalid length for a Base-64 char array.
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Oct 15, 2011
I seem to be having a problem with controls that I am creating as new classes (not UserControls) inheriting from an existing system control. Everything seems ok while I create the control code, through to the compile (which is successful and adds the control to the toolbox) and dragging the control from the toolbox to the GUI surface. However, when I then debug or compile the project, I get a message such
[Code]...
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Jan 27, 2010
Do While rdr2.Read()
Dim var1 As String = rdr2.Item("Week").ToString
Dim var2 As String = rdr2.Item("L1").ToString
Dim var3 As String = rdr2.Item("L2").ToString
It generates the following error: A first chance exception of type 'System.Data.SqlServerCe.SqlCeException' occurred in System.Data.SqlServerCe.dll
Interestingly, if I use a numeric value for the variable it for LSArraytemp, it writes to the database no problem at all.
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Aug 9, 2009
My colleague gave me a DLL that manage all database business. I wanted to invoke a function that uses Stored Procedure and return the search result. In the function receive a parameter type in ystem.Data.IDataParameter[]. Below is my codes.
[Code]...
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Apr 25, 2012
I have a function (on vb.net) to get a data from a XMLWebService:
[Code]...
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Feb 19, 2010
I added this lines in the form load of DataGridPrinter by Merrion in the codebank..[code]Unable to cast object of type 'System.Data.DataViewManager' to type 'System.Data.DataTable'.
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Dec 31, 2009
every time i run this code i get the same error
Unable to cast object of type 'System.Data.DataTable' to type 'System.Data.DataView'.
the code is
Dim plmExcelCon As New System.Data.OleDb.OleDbConnection
Dim cmdLoadExcel As System.Data.OleDb.OleDbDataAdapter
Dim PrmPathExcelFile As String
[Code]......
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Apr 25, 2012
I have propetie get set classes, and a constructor to quickly set them all.The only concern I have is that the byval in the constructor class and the byval in the set() properties, might be inefficient because the parameter is copied twice? Should I use ByRef? Or is that too dangerous?
'Config data for an Environment.
Public Class Environment
Private msEnvName As String
[code].....
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May 20, 2011
Does anyone know why on earth in my linq to sql designer classes, that I am getting type not exist for any system, system.data, system.data.linq nameapces?I am trying to convert a website to a web application and this has me stumped. In order to create an object I have to use the Global. prefix on all the namespaces.
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Apr 13, 2011
I have done programs in the past with VB6 using the winsock control to receive data to be processed. I would like to do the same thing in vb.net but I am having problems. I have done numerous searches and consulted numerous books and articles, but haven't found the best approach for accomplishing the following.
I would like from 1 to 20 clients to be able to send a string to the server to be processed. It would be nice to if the clients could connect to same port and use async processes to open/accept more connections. One of the books (Visual Basic 2008 Recipes) has a recipe for creating "Multithreaded TCP Server that supports Asynchronous Communications".
I am trying to base my program off of that example and modify it for my application. The problem I am having is how to share data with the Main form and the classes that handle the communications. The TCP class has two classes contained in it. One class for listening for connection, beginning the accept client and the other class (clienthandler) for completing the connection and getting the data. I would to be able to get the data from the clienthandler class and post on the main form. I have trying to have a public property for the data but I think my confusion comes in because the clienthandler would be created new for every new client. The mainform would not know how many of the new clienthandlers were created etc.how get the data to the main form and clear the data when done. I have even considered putting data into MSMQ and having main form pull data out.
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May 30, 2009
I am working in vb2008. How to store Class/Structure instance data into a database as single objects.
SomeClass
.name
.address
.age
.etc
Say I have a hundred instances of "SomeClass" stored with data. Is there a way that I can store each of my hundred instances as a hundred objects to a hundred Access database records. I am trying to avoid having to mirror my class structure into a datatable and treat each instance as a single object which can be stored into a single database column name.
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Jan 23, 2012
I have two classes, one nested in the other. [code]Neither "Name" or "ID" are unique between operations and records.I wish to construct a dictionary using LINQ = Dictionary(Of String, Of List(Of Integer), whereby the keys are uniqe examples of Names in my collection and the values are the collective set of distinct IDs that are associated with those names.
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Jun 13, 2012
How can I structure my classes so that the user interfaces though a single class while the supporting classes are hidden from their view? I think its best understood in an example:
Public Class MyInterface
Public Economic as EconomicClass
Public Sub New()
MyBase.New()
[code].....
So you might ask why am I even separating them? It's strictly for others who will be working with this interface. I need to funnel them though a logical structure:
interface.Economic.MyMethod
interface.Currency.MyMethod
etc
This way everything is already handled for them in the background and they only need to run the method they need. I don't know if I can have it both ways in VB.NET.
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May 5, 2011
I am using VS 2008, Office 2007, and Win7 Home Premium on my system.I have a simple application which should be a breeze to build. All I am attempting to do is pull data from an Access database with four small tables into a data grid on a windows project. Should be simple, set up the data connection, choose a datagrid from the table in the data source view, drag it onto the page and done, right?I can't get it to work. It will all work fine until I attempt to run or debug the project. The data will not show up. The data grid does, but I get this error: A first chance exception of type 'System.InvalidOperationException' occurred in System.Data.dll
As I said, the project seems to build fine, but it will not pull the data. After the initial build I get the message that Windows will show this page in Compatibility View. Is it something with Win7 Home Premium, or a setting somewhere?
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