When using SQL connections in my program, will I have to open and close the connection and the data reader each time I want to access the database ?
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I want to know what is the right way to close my Database connection while its open.
This is how i open my connection.[code..]
In my program, I have a timer with a inteval set to 1000ms. The timer is executing a MySQL-command, and right now I'm opening and closing the connection each time.
View 5 RepliesI created a connection to a Microsoft Access database by using the wizard. Now in the server connections I see my data connection to the db. I'm trying to create a method to compact the database, so I used JRO to do it. To do it however, an exclusive access is required, and when I try to call the method I get an exception.
View 4 RepliesI have an access 2007 database that I have been developing a front end for in vb.NET for the past 3-4 weeks using vs2008 in a Windows 7 enviroment. Yesterday I started getting an error of "Your network access was interrupted. To continue close the database and then open it again." This happens in the Form Load on the line:
gotData = Me.LeaguesTableAdapter.Fill(Me.LeaguesSeasonsPlayersDataSet.Leagues)
I can go into access 2007 and view all the data fine and in vs2008 I can view the server explorer and browse the tables. However, under data sources if I try and preview the data, I get the same error message as before. What confuses me the most is that the database is not stored on a server is just stored in My Documents. It was origionally stored on my desktop pc but has been copied to the My Documents on my laptop. But as I mentioned previously it has been working fine and has just all of a sudden started throwing this exception by my Try Catch routine. FYI I have tried creating a new DB and importing the tables from the old DB but this hasn't solved the problem either.
i make a class and when i call on form then that error occurs "ExecuteNonQuery requires an open and available connection, the connection Current stat is close "
Class Code isImports System.Data.SqlClientImports System.DataImports System.StringPublic Class DatabaseKits Dim Cn As New SqlClient.SqlConnection Public Function BuildConnection() As Boolean Try Cn.ConnectionString = "Persist Security Info=False;Integrated Security=True;Trusted_Connection=Yes;database=BizAimsPro2008;server=Server-2k3s" BuildConnection =
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am trying to open a connection to an access db using the following:
vb
Dim cmd As New OleDb.OleDbCommand(QUERY, New OleDbConnection(CONNSTRING))
cmd.Connection.Open()
'dim dr
cmd.ExecuteReader
On the cmd.ExecuteReader line an error is being thrown whose message is unknown .
The connection string is as follows:
Provider=Microsoft.Jet.OLEDB.4.0;Data Source=MYDB.MDB;Jet OLEDB:System Database=MYWG.MDW;User ID=USER;Password=PASSWORD;
SQL connections confuse me sometimes In almost every SQL related code on the internet the routine is like this;
* Open connection
* Execute SQL command
* Close connection
Is it good practice to just open a connection when the application starts and use that connection until the application closes?I know that sequential connections are required when processing more queries, but what if I need to poll a certain Table every x seconds? Isn't is better to keep that single connection open for as long as the application is running (and re-open when a failure occurs) instead of opening a new connection every x seconds?
I am trying to open an Oracle database connection in vb.net 2008 in order to issue a Select statement and the populate a listbox with it.
My code is as follows:
Dim orclstr As String = _
"Provider=OraOLEDB.Oracle;" & _
"Data Source=10.0.0.77;" & _
"User ID=myuser;" & _
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Obviously, I am doing something wrong, but I can't figure out what.
I'm using the following code to open a pdf document in Adobe reader print and close Adobe reader. It works well in XP but when i try the same in win server 2003 or win server 2008 I get a message in Adobe Reader saying it could not locate the file to be loaded. Any thoughts or guidance to resolve this behaviour will be great.
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Should I open a connection to MySQL at the load of my application and close it when you exit or should I open and close the connection only when I need to run queries?
View 1 RepliesI'm using a OleDB connection to a access database. I'm entering a row into the database to set some user preferences. What i need to get is get back the row ID of the row I just entered. I'm more familiar with PHP and with PHP I use use this entry
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how to open a PDF file attached in ms access using Adobe PDF Reader tool?how to connect this tool with database?
View 12 RepliesThe fact is I'm making an application, which users can install by using a Setup file...once installed the data in the database can be updated by a centralized server. To do this, they can insert a DVD/CD-ROM and export the necessary data towards it. I need to do it that way, because some of the users who really need this data will be using stand alone computers.The application gets it's data from a mdb-file and the connection remains open as long a person works with the application (maybe not the best way to do, but I know :-) )...when the user uses the application, he can perform an export...this exports the .ini-file and pictures (which works fine), but he also needs to export the mdb behind the application...I already tried connection.close() before and connection.open() after the System.IO.File.Copy...but that doesn't seems to work.
View 2 RepliesI am working on a VB.NET project that grabs data from an Access DB file. All the code snipeets I have come across open the DB, do stuff and close it for each operation. I currently have the DB open for the entire time the application is running and only close it when the application exits.
My question is: Is there a benefit to opening the connection to the DB file for each operation instead of keeping it open for the duration the application is running?
I have created a data source connection to an access db by using the wizard in vs2008. I have then used this as a data source for crystal reports. My user would like to put the database on a network and reference it there. Is there a way to set a new path for this data source during runtime?
View 4 RepliesI have a problem reading data from an RFID-reader. I connect to the reader by tcp and wait for DataAvailable to be true, then reading the data until I got a end of data character. Then I just go back and waiting for a new DataAvailable. This is done in a own thread for the function.
There seems to be some kind of timeout, If I don't got any data in a couple of minutes, then it just sits there in the do/loop waiting for DataAvailable. I hold the card to the RFID reader, it beeps, but there is no data available. I don't get any exeptions, and the information says that the clientsocket is still connected. Are there anything more I can check?
If I put the card to the reader in a minute-interval it seems as this will never occur. So 2-3 minutes idle:ing seems to do this.
Here are my code to read data from the socket, I have taken away some irrelevant code:
Sub test(ByVal ip As String, ByVal port As Integer)
' this sub is meant to run forever
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I have a .mdf file that I open through an Open Dialog Box and use in a ConnectionStringBuilder (where I have the user instance set to True). Later, in one of my button clicks, I try to open the connection (connection.Open()). It then gives me an error as follows: "Generating user instances in SQL Server is disabled. Use sp_configure 'user instances enabled' to generate user instances."
Here is my code:
Option Strict On
Imports System.Data.SqlClient
Public Class frmMain
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I am currently working on a login page using vb.net. I would like to know how to make connection to an access database and verify that the user logged in is a valid user
View 6 Repliesi want to know how to open a connection to database from vb.net
View 3 RepliesI'm trying to create a simple Data Grid that will automatically save changes. So far I have a data grid connected to a MS Access 2007 Database that reads the data. I can create new fields in the Data Grid, but I need to program to save the data automatically to the database on update (or on close).
View 6 RepliesI have a basic calendar schedule i want to loop through and then do some checks. My first data reader works fine. But as soon as i put in the second data reader it does not finish.Here is my code
Dim mycommand As New MySqlCommand
Dim mycommand2 As New MySqlCommand
Dim myData As New DataTable[code].....
Basically the above code looks up distinct calendar entries in the database.i then loop through the entries and put the items in a list view.The code above will list about 1600 rows.in the above code if i uncomment the 2 lines the system will break It will on display one line of code. What im trying to do in the second query is to see if there are double bookings in the database.
How do i make it so when i close my client the server will restart listening and allow another client to connect.
View 3 Repliesi am doin project using vb.net 2005 and using this sql query for connection
sql = "select username from login order by username"
con.ConnectionString = "Data Source=" & hostname & "; Initial Catalog=college;integrated security=sspi"
but m getting the following error:
Cannot open database "college" requested by the login. The login failed.Login failed for user 'CI4Admin'.
I am developing an application that is using a Jet database (Access 2007). The database is local to the project (e.g., on the same drive and in the project directory). Any time I attempt to access the database (to create another DataSet, etc., via designer, etc.), I get the ubiquitous "Failed to open a connection to the database" with:
No error message available, result code: E_UNEXPECTED(0x8000FFFF).
Opening the Database Explorer and attempting to attach to the database results in the above as well. There are no apparent locks on the file, etc., and I'm the sole developer for this.
I'm trying to a open a connection to a local database and no matter what I try it just won't work (I'm pretty new to SQL Server and VB for that matter) I tried using 'sqlconnection' with different connection strings but none of them worked or gave me any useful error messages so I tried using 'OleDBConnection' instead, this hasn't worked either and it gives me this error instead:"A first chance exception of type 'System.NullReferenceException' occurred in MyProgram.exe"
Here is the code I am currently trying:
Private Sub MemDetailsSearch_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
ConnectionString = ("Provider = Microsoft.Jet.OLEDB.4.0;" & "Data Source = Database.sdf")
DataConnect = New OleDbConnection(ConnectionString)
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I installed SQLExpress 2008 on my computer this afternoon and have been trying to create a new database and open a connection to it. I found this code online and tried it:
Dim
conStr As
String =
"Server=MSSMLBIZ;Database=;Trusted_Connection = yes"
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can data reader be used as a data source for a grid control?
View 5 RepliesI have a connection string in my app.config:
Code:
connectionString="data source=.sql2008 ;Database=Database1; Integrated Security=FALSE; Persist Security Info=True;" />
How do I change to another database (one of many) without using multiple strings? Can I change while the connection is open?
Code:
Dim myConn As New SqlConnection(System.Configuration.ConfigurationManager.AppSettings("ConnectionString"))
I keeping getting an error.Seems to be the connection string.Error happens at connection.Open()
Error Message:Cannot open database "C:UsersJEREDocumentsVisual Studio 2008ProjectsBaseball2009Baseball2009DatabaseBaseball2009.sd"
requested by the login. The login failed. Login failed for user 'JERE-PCJERE'.
Imports System.Data.SqlClient
Public Class Field
Private Sub Field_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load[code]..........