Can anyone tell me How do I solve this error.Error: NullReferenceException was Unhandled - "Object reference not set to an instance of an object."
Line: Dim reader As OleDbDataReader = dbCommand.ExecuteReader()
Database: MS Access
IDE: VB 2010 Express
[code].....
I am using Microsoft visual basic 2010. I am using the following code to connect to a local access database. After the line myReader = cmd.ExecuteReader () no code runs. I am not receiving an error message.
Dim connectionString
As String =
"Provider=Microsoft.ACE.OLEDB.12.0;data source=C:UsersmikeDocumentsFCE_Database.mdb"
[code]....
I have used this method to connect to the same database multiple times in the same program without a problem I've also tried using OleDb with the same result.
my problem is first of all i created a button and a datagrid to display the mydb.mdb in it the code behind that is as follows when i click on button the students table from mydb.mdb (which resides in my pc) needs to display in datagrid
<code>
using System;
using System.Collections.Generic;
using System.ComponentModel;
[code]....
the error is at Line: dbReader = cmd.ExecuteReader();an the error is :ExecuteReader: Connection property has not been initialized.
I have o problem on my codes sqldr = sqlcmd.ExecuteReader when i debug the program error says ExecuteReader requires an open and available Connection. The connection's current state is closed. i dont know what its means that error..
View 1 RepliesWith DbCommand I'm trying execute this SQL statement[code]...
But when I run each command from strCommand standalone then everything works fine.
I'm using VS 2010 Professional and SQL Server 2008 R2 Express.
I am trying to add an order by case statement in the dbcommand.commandtext but i see that no rows are returned. I want to assign priorities for colors in the case statement. This would help me avoid create a new table to priorities and rewrite a lot of code to map the foreign key.[code]
View 2 RepliesWhy I am getting the following error:
Error: "ExecuteReader" is not a member of 'System.Data.OleDb.OleDbConnection'.
The following is the
Private Sub txtSearch_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtSearch.TextChanged
Dim MyReader As OleDbDataReader
If txtSearch.Text <> "" Then
[code]....
I have reviewed the prior post on this topic and am confused.
Private Cn As sqlConnection
Private Cmd As sqlCommand
Private Da As sqlDataAdapter
[code].....
How to use the ExecuteReader calling a stored procedure with a parameter array?
View 1 RepliesI am getting an ArgumentOutOfRangeException when I try to run the following code,[code]the table that is being read has a single row of data, the database and connection are fine as I can run INSERT/UPDATES etc but wherever I have used a datareader I am getting this exception each time on the "Using reader As MySqlDataReader" line.
View 2 RepliesI am executing stored procedure using ExcuteReader() command. If I execute Stored Procedure in SQL server it is taking 2 secs. But in code taking around 2 mins. I tried DataAdapter.Fill(). Still the same.
What is wrong in the code?
spString = "usp_graph"
sqlcmd_q.Connection = sqlCnn
sqlcmd_q.CommandText = spString
[Code]....
Dear friends I am new in .net world and I am trying to display a single row to a literal. I prefer VB so my code is as follows but I'm getting the error "ExecuteReader: CommandText property has not been initialized".I also tried sqlCmd.CommandText = "getLastModificationDateTime" without the EXEC statement
View 3 RepliesPublic Class app_mainform
Dim mssqluname As String
Dim mssqlpword As String
[code].....
i have this code in form1 at buttonpreview
[Code]...
i have problem with my code
here is my code
Public Sub increment()
Dim dr As SqlDataReader
If con.State = ConnectionState.Closed Then
[code].....
Public
Class Form1
Dim conn
[code].....
i have app that connects to a mysql db.i get data from the db with executereader.but i want to execute some sql depending on the result from a other db.but i get a error when doing ExecuteNonQuery() when the reader is still open.Here's a part of my code where the problem occures.
Code:
tracecom.CommandText = "select * from testsms left join customer on customer.id=testsms.id where date_sub(now(),interval 1 minute) > testsend"
tracerd = tracecom.ExecuteReader()
If tracerd.HasRows Then
[code]....
I'm getting the error below for this SQL statement in VB.Net 'Fill in the datagrid with the info needed from the accdb file
[Code]...
I am using below mentioned Ado.net function and resultset bind with grid view, however I am getting the duplicate rows in the resultset.
[Code]...
I have a program using the OleDbCommand to read an indexed Access database. [code]I notice that when step debugging the program, the file is not being read in correct order.Example: it will read the record with "B" in the D01 field before a record with "A" in the same field.The record with "B" is the second record in the database.I do note that all records in the database are read before exiting the loop, just not in any apparent order.
View 5 Repliescould someone help me with some simple coding methodology for doing database searches within the ExecuteReader function that will return results regardless of case?For example, if the variable to search for within the database is John Smith,I would want the search to be successful if john smith is the user-provided variable.
View 8 RepliesI have a stored procedure that repeats a block of T-SQL statements using WHILE logic until it finds a matching record in a table. When I execute the procedure directly from the SQL Management Studio, it works and returns a record, even when the statements within the WHILE logic have to be repeated over and over again before a matching record is found.
However, when I use the same stored procedure as the commandtext property of an sqlcommand object in Visual Studion 2008 (VB) and call the executereader method of the sqlcommand, the resulting SqlDataReader will only return a row if the T-SQL statements within the WHILE logic find a matching record after a single pass. If it takes more than one pass to find a matching record the SqlDataReader does not return a row. It's like it abandons the execution of the stored procedure after the first pass of the statements within the While logic, disregarding the repetition.
is it possible to skip forward or backup to the previous record in a database within a Do Loop of an ExecuteReader routine? For example, with the following code:
DMDatabase01.Open()
DMCommand01 = New OleDbCommand("Select * From DB01Table01 Order By DB01F01, DB01F02", DMDatabase01)
DMReader01 = DMCommand01.ExecuteReader()
Do While DMReader01.Read = True
[Code]...
I have the need as part of a larger data comparison program to not always read the next sequential record - at some points I want to go back to the previous record, or skip forward to the next record, but stay within the Do Loop.
I am using ExecuteReader commands to read records in large external databases. Part of my program logic requires that a condition of the database be examined without reading another record - for instance, I want to know if the database has reached the end without reading an additional record.
[Code]...
Using VS 2005 and SQL Express 2005. This WinForm application runs fine on 5 out of 6 stand alone computers that is it installed on. The 6th computer is slightly older running XP sp2.As I understand it, using DbDataAdapter will perform the open, close and dispose functions for you. Therefore, Pooling should not be an issue. I am thinking that the default 15 second time out setting may be the cause?? There is some MultiThreading that will also use DbDataAdapters in the same manner but only 3-4 would be firing at the same time.The connection string is Data Source=(local)DataBase;Initial Catalog=Code;Integrated Security=True The command which throws the exception is If CodeDataAdapter.Fill(CodeDataSet.CodeTable) > 0 Then...So I am thinking that adding Connect Timeout = 60 to the connection string even though the 15 second default seems like a lifetime. Could this 15 seconds be eaten up if some other process or application takes over?
View 3 Replieswhat is wrong with my code and I get no feedback from my button click event, i have imported. ( code Below) and i have tied differrent combinations of the code without sucess.maybe add extra to my code for the list to show open Port or closed ports.
Imports System.Management
Imports System.Management.ManagementObjectSearcher
Imports System.Management.ManagementNamedValueCollection[code].....
I realize this post is rather long, but I wanted to give all the information up front instead of people having to ask me for more information.At the end of the re-installation of Visual Studio 2008, there is this message:
"Microsoft SQL Publishing Wizard: [2] Error: Installation failed for component Microsoft SQL Publishing Wizard. MSI returned error code 1638" in the log file dd_error_vs_procore_90.txt.
I have searched on Google for this whole message and found some references to this error, but I have done what they said worked for them and it did not fix the problem for me.When I searched for just "MSI returned error code 1638", I got that it cannot install something because it is already installed:"Another version of this product is already installed. Installation of this version cannot continue. To configure or remove the existing version of this product, use Add/Remove Programs on the Control Panel".In Add/Remove Programs I see these two programs:
Microsoft SQL Server Database Publishing Wizard 1.3
Microsoft SQL Server Database Publishing Wizard 1.4
Are these programs/versions what the error is refering to? Am I safe to remove them and depend on the similarly-named item which would be newly installed with Visual Studio 2008 - "Microsoft SQL Publishing Wizard"? I still use SQL Server 2000 and 2005 on my computer, as well as 2008. I had installed VS 2008 on my computer before without this problem and also have VS 2005 and 2010.
Any ideas on how I handle the following error thrown in the SqlDataAdapter.Fill as a result of the BeginTrans in the callee?
System.InvalidOperationException = {"ExecuteReader requires the command to have a transaction when the connection assigned to the command is in a pending local transaction.The Transaction property of the command has not been initialized."}
[code].....
Public Sub ExecuteTransaction(ByVal connectionString As String) Using connection As New OleDbConnection(connectionString)
Dim command
As New OleDbCommand()
Dim transaction
As OleDbTransaction
[Code]...
The program has errorhandle and write log function, however, it could not catch the error message in the program.
The following error message in Event Viewer. Error Module: oleaut32.dll ,version 5.1.2600.5512, error code: 0x000048f9