ADO.NET :: Re: Idatareader Data Access?
Feb 18, 2011Did you check this c# - SQL Data Reader - handling Null column values - Stack Overflow
View 5 RepliesDid you check this c# - SQL Data Reader - handling Null column values - Stack Overflow
View 5 RepliesI had a web application that was binding a IDataReader to a repeater control. I converted the project from 3.5(2.0) to 4.0 and then I received the error:
An invalid data source is being used for rptData. A valid data source must implement either IListSource or IEnumerable.
So, I used a datatable instead and the binding worked. So it seems that they have removed this functionality with .NET 4.0.
I'm populating a DataList using the IDataReader object and it works fine it the reader contains data. If the data is not present it displays nothing. I want to capture that situation and insert a verbiage such as "No data" or something like that. I've tried to test the datareader for various conditions such as Null, String.Empty, or plain " " but nothing worked. Is there a way to make this happen? Below is my code sample for your review.EJM.Note: It has to be done programatically as I'm building this for a web part.
[Code]....
I heard that using "Using" Block avoids Connection Leaks in IDataReader. Is this correct??? If so how it will do that???
View 2 RepliesI've been out of the ASP.Net arena since 1.1, and I'm starting to get back into it after a hiatus.
In the past, I would generally create SqlDataReaders, wire them up to pull from tables in a database via direct sql or accessing database views (mostly in MSSQL), grab the data, and display it in some datatable, or datalist.
Modifying data would usually be calling a stored procedure in the database to add/modify data, and then retrieve it afterward.
Now that I read up, I see there are alot of new things in ADO.Net world; strongly typed datasets, auto-generated adapters, etc.
My question is, does anyone have a good reference on best practices (or a book recommendation) on how to handle data access, and data manipulation and display now? I'm assuming that there are more automatic ways to show and manipulate data than before, but the new details are quite vast (which is good), but slightly overwhelming for me.
i am facing some problem in update, edit and even create new data into my access database using data detail view. i am using microsoft visual web developer 2008, i can do the same when sql server database were to tore the data. but when i try to do the same using access database, an application error. may i know whats going wrong? and how to solve this problem?
View 7 RepliesHere's a short explanation of my asp.net project.
1) the default page loads, it will read the Windows Login of the user opening the page.
2) I'll check if this login exists in a table stored on the webserver.
In this Access Database, there's a 2nd linked table, pointing to another access table on a network location. Now, I want to read data from this linked table. However, at this moment I receive an error:
"The Microsoft Jet database engine cannot open the file '\<ip><shared-folder>statistics.mdb'. It is already opened exclusively by another user, or you need permission to view its data".
Some extra info:
- The network folder has read and write permissions for everyone
- the user and group permissions on both access files are set to read/modify/administer for the Admin user (on the tables I want to read from)
- IIS authentication on the server is set to "Windows Authentication" (this is needed so I can read the Windows Login from the user). All other authentication modes are disables (like anonymous, ...)
- When the error occurs, no other program or process has access to the statistics.mdb (so, it can't be locked by someone else)
- the web.config files access connection string looks like:
<add name="AccessConnectionString" connectionString="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=\<IP><shared-folder>statistics.mdb;User Id=admin; Password=;" />
Like I said before, in this statistics.mdb file, there are 2 tables. One normal table, and another linked table (pointing to a network location)
Searching for solutions, I discovered the following:
- if I don't use linked tables, everything works fine (however, I have to use this linked table)
- even if I connect directly to the table in the network I receive the error. So, I'm pretty sure I don't have sufficient rights to read from this table.
I read that not the Admin user is opening the file, but actually a user called ASP.NET. This user doesn't have the correct rights to do this. However, I'm not sure if this is true.
I made a project to use the access membership provider from [URL] and it works. But I need to edit my database but when I configure my database, I cannot see the tabel, I can only see the queries in mdb file. when I select the field from query, I am unable to update it. My code is as follows:
[Code]....
I have a data type mismatch while inserting into a number field in an access database using a parameterized query.I think this should be pretty simple but I am still learning a lot.
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I have some commented out as I am working one field at a time. The working fields are textboxes and the non working ones are dropdown lists. But I think it may be the field that the list is drawing from? Not sure.
I have one question here.I created a registration form using asp.net and c#.
when I entered all the fields in that form and hit the register button the data will be inserted in to the database table called xyz table
in that table I have an id field which is a text field in access database consists of guid starting with letter P
when I inserting the data from aspx form...the guid is not inserting into the table.
one of my datarecord in that table with the id field is like this.(.P11111111-1BBB-4444-A9D1-111111111111)
need to insert anoother record in that table that field must be generate with the ID starting with P..its an guid.. the creating guid in the aspx.cs page..??
I have a form wilh couple of Drop downs and text boxes and a Data Grid View which displays data from Access Table. When I hit add button on the form, I can see the data being added to the Grid View. But when I close the form and open the Access Database File (.mdb), the respective table is empty. The Access Table is not being updated. Second time if I open the form, the Grid View is also empty.I am pasting my code here.
Public Class Home
Shared OleDbConnection As System.Data.OleDb.OleDbConnection
Shared ExpensesDataAdapter As System.Data.OleDb.OleDbDataAdapter [code]....
Iam facing the problem with creating the Data Access layer using Dataset.xsd file and How to access the data from the file.
View 2 Repliesgive me sample code for insert data to MS ACCESS from grid view using dataset.
View 5 RepliesI am starting a new project in ASP.NET (With silverlight) - I would like to get expert opinion about how to design the data access.I can use DataAccess Layer with SQL helper, but the challenge is every new field that I add needs to be added in the sql helper.I am trying to see if there is a way to design the system, so that it appears in the front end when a new field is added. I don't want to have in the ASPX files (binding in controls) I want to have ability to change items in code. Essentially I am trying to see the best option to have a database application.
View 1 RepliesI am using the following code to insert data into an Access Database. Also this is the sqlcommand.
UPDATE TASKS Set Notes="bunch of html code" WHERE APPLICATION="SomeApp"
However I get an error. How can I input data regardless of what is in the command area?
'Dim ConnString As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|AddCol.mdb"
recommend a data access class / helper class for Access databases, similar to the sqlhelper class found in the (Data Access Application Block)?
View 6 RepliesSo I have created a log-in screen that allows you to create a user at the same time. I wanted to make sure that if there was already a UserID registered that if a user tried to register with the same ID that an error message would show rather than my whole website crashing.
This is my code:
[Code]....
The code to place the data into the database works fine by itself but when I put it into this if statement the data no longer goes into the database.
If this the correct way to do this for making sure that a user cannot create a profile with a user id that is already present or is there a simpler way? I have tried to do it with a customvalidator but that did not work at all.
Is there anything missing in IIS 6.0 that prevents me from (Insert into table) using MS-Access?
Explain: The application works fine under Visual Studio 2008 IDE the insert into table works fine with no error, Also I tested with hosting provider and works fine with no problem. but now I have published the same exact app in a dedicated server windows 2003 with
IIS 6.0 .NET framework 2.0 with latest service pack I gave IIS_WPG write/modify access to the folder where MS-Access database is located and database but at the time of insert an error pop-up. I need to install in the Server or settings in the IIS to recognize my MS-Access db is it some office runtime that I am missing. (BTW I am using OLEDB connection string in my C# )
Using System.Data.OleDb;
I can retrieve data off of it with no problem but when I try to insert is when it fails I thought the problem was Access Rights but I do not think is the case.
Dim ds As New AccessDataSource
ds.DataFile = "c:InputTest.mdb"
ds.DataSourceMode = SqlDataSourceMode.DataSet [code]....
This is my code and i am only able to edit the one data under the category school.But what i nd is to edit the other categories like the name,email...etc..how do i modify my code in the update command.Another thing is to delete the data how do i do that?
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I have a code to link to sql can anyone give me the same code for microsoft access....
try
{
int videoID = Convert.ToInt32(Request.QueryString["ID"]);
SqlConnection conn = new SqlConnection("server=WEBDESIGN-PC;database=Credentials;uid=sa;pwd=Azeem;");
conn.Open();
SqlCommand cmd = new SqlCommand("SELECT * FROM videopath WHERE videoID=" + videoID, conn);
SqlDataReader dtr = cmd.ExecuteReader();
dtr.Read();
FlashVideo1.VideoURL = Convert.ToString(dtr["Filepath"]);
Label1.Text = Convert.ToString(dtr["Filename"]);
conn.Close();
}
catch (Exception ex)
{
Label1.Text = Convert.ToString(ex);
}
finally
{
}
I have a search box on a web application that is to use a query I have built in Access to search through projects to find any that are related to the text entered in the search box.
The query in Access is just made up of parameters that use wildcards to search through all the fields. In Access the query works fine and returns the correct data but when I try and link this all up to a ListView in Visual Studio, the ListView just diplays the message "No data was returned"
Below is my page-behind code, hopefully you can see why it is not working but it looks like it should work to me.
[Code]....
We are using a tierd design with a Data Access Layer and classes for everything we need. This serves as an advantage because we do not have to write querys over and we can separate the Presentation layer from the Data Access Layer and Business Rules.I have always in the past populated GridViews, DataLists, repeaters,etc with SqlDataSources. This is what I have become accustomed to and I feel like it is simple. For querys such as Select * from Members, I feel like using a DataSource is simpler than having to go in the code and calling methods to populate and DataBind these presentation controls.
I am working with a gentleman who has introduced me to the world of Data Access Layers and we are breaking everything down into simeple, but effective queries to populate controls and do what we need to accomplish with this application. He is not very approving of using any type of DataSource. We are disagreeing on the time and place to use these class methods to call the database.So my question is, which is more widely used in the programming world? Do most people use DataSources to populate presentation controls regardless of the Data Access Layer they are working with? Which type of queries are best suited for a DAL - simple, populating queries or complicated joins and upserts?
I use ObjectDataSource and DetailsView for Updating records . my Bll input parameter method is an Object instead of regular parameter . So i though i could make my own ObjectParameter in ItemUpdating event of DetailsView and i need some modifiation on the data that user input on boudfield in detailsView . I don't know how to access BoundFiled data from ItemUpdating Method of DetailsView.
View 1 RepliesI have a lot of members data to enter into the ASPNETDB database. How can I read this data from an Access data file and input into the SQL database. All data is for user Names and Password,
View 1 Replies