VS 2010 - Return Data Reader Or Dataset / Datatable
Dec 18, 2010
Had a datareader question.
Return myDataReader I have a function which is retuning a datareader to various sections of my website which is then being bound to dropdown lists, gridviews, etc. Normally the last line in a function when is the data reader and connection getting closed? Is it best practive to return a data reader or a dataset/datatable (or something even better than these two)?
I'm making the leap from using all the 'wizards' that are built into VS, and have been doing more with code-behinds. But, I'm curious as to when/why I should use a reader, versus a databable, table adaptor to "manage" the data returned from a stored procedure. Typically, the data is to be displayed on a webpage, and not written back to the database. What's the difference? When should I use one over another?
I want to take my return value from sql server to c#.
ALTER procedure [dbo].[userss](@email varchar(100),@password varchar(25),@name varchar(250),@DOB varchar(20),@acc_vari int,@ip_address varchar(50),@vari_code varchar(7) ) as begin declare @uid int select @uid=uid from users where email='12we' if(@uid>0) return 0 else insert into users values(@email,@password,@name,@DOB,@acc_vari,@ip_address,@vari_code ) end
In this i want to take return value "return 0 " from sql server to c#.
Our ASP.NET application allows the users to review any number of PDF forms. A simple listbox holds filenames and the forms are displayed inside a standard iFrame. The setup is simple and effective: when the user clicks on a filename, that filename is loaded into the iFrame, and shown to the user.
Users are allowed to digitally sign the forms. For appearance purposes, a bitmap of the user' signature is generated and placed in the appropriate location of the PDF form.
The bitmap file format is GIF, and the background is transparent.
We use iTextSharp for form-filling, and we also use iTextSharp to place the bitmap on the forms. Nothing special.
We can readily verify that the signature bitmap is correctly placed on the form, and that the bitmap itself is definitely transparent.
After placing the bitmap of the user' signature on the form, the form is reloaded and displayed to the user (for verification) and, in most cases, the forms do not display the bitmap. Opening the PDF reveal that the bitmap has been placed and is definitely visible in Adobe Reader (9 and 10 - these are the versions available for testing).
Experimentation and quite a bit of research seems to suggest that the problem lies in caching. One of the possible solution/suggestion is to append a time-stamp or a GUID to the URL, when loading the form after applying the bitmap. In theory, this should prevent Adobe Reader from using a cached copy of the PDF form.
We have tried appending a time-stamp and/or a GUID, without any success: the forms still display without the bitmap. At the risk of repeating myself: the PDF form is correctly signed, and the bitmap is correctly placed. It is just not visible.
This problem seems common to users running the application on intranet web servers (IIS 7). The one application instance running on public web server (IIS 7) does not seem affected by this problem.
As mentioned, the GIF file generated by our application has a transparent background. In almost all cases, Adobe Reader (9 and 10) seems to understand and respect the transparency of the bitmap.
In one very peculiar case (when the application is running on a Windows 7 64 bit machine with IIS 7), when the bitmap is placed on the form, it becomes opaque (complete loss of transparency).
Again, the problem seems related to Adobe Reader, because the bitmap being applied positively sports a transparent background.
I need your help / guidence for doing custom paging in c#, through sqlserver. so that i can have data in dataset/datatable according to the pagesize given, not all the data in dataset. some code /url .......with full discrption if possible.
I am trying to return a dataset. I must be doing something wrong. The returned dataset in this sample code indicates there is a datatable, Users, but there are no datarows. What am I doing wrong? This example is only using the rows.count, but of course I really need to use the whole datatable as the datasource for a gridview.
Public Function getmyds() As DataSet Dim dsUser1 As DataSet = New DataSet() Dim tbUser1 As DataTable = dsUser1.Tables.Add("Users") tbUser1.Columns.Add("UserName") tbUser1.Columns.Add("Days Remaining") tbUser1.Columns.Add("UserAccountControl") Dim rwDefaultUser1 As DataRow = tbUser1.NewRow() rwDefaultUser1("UserName") = "John Smith" rwDefaultUser1("Days remaining") = 100 rwDefaultUser1("userAccountControl") = "Enabled" Return dsUser1 End Function
I'm using a table adapter to perform my queries. I'm sure I'm missing something really easy, but I can't figure out how to return the number of rows returned from a query to a dataset used for a GridView.Basically, I want to display a message "No records exist for your selection" by testing for ReturnedRows = 0.
Excerpt of C# code:
handoutDSTableAdapters.handoutTableAdapter handoutsAdapter = new handoutDSTableAdapters.handoutTableAdapter(); gv_Handout.DataSource = handoutsAdapter.GetDataByDoctor(Int32.Parse(ddl_MD.SelectedValue)); gv_Handout.DataBind();
I have a Gridview and two link button in that GridView , one link button click is to add edit row ( Edit ), one link button click is to select row ( Select ). I have a dropdownlist inside row which selected when i click link button Select in the gridview edit template, as of my business logic i need to show the dropdownlist only when the user clicks Edit button and when the user clicks Select button . That mean when the user clicks Select button then they clicks Edit button on the gridvview i should allow him to edit the dropdownlist (showing the value to the user through a label).
When I click Select link button , then I click Edit link button . They have errors : Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index" I don't know what error?. How to fix it
In a VB.Net project I use the Adobe PDF Reader (AxAcriPDFLib) control to display a preview of a selected PDF document whereafter the user can double-click upon the selected listbox item to enjoy a full screen view of the relevant PDF document. see the attached sample in this regard. Is there any way to emulate this in ASP.Net?
I have some code in my vb.net code behind that queries a database, and if there is data, outputs it from the codebehind to a datalist on my asp.net page. In addition to sending the data to the datalist on the page, I need to take the value from "mbillaty" that is returned from the sql query, and have that value be the selected value for a drop down box also on the page. I can get either the datalist to fill, or the selected value for the dropdown box to be selected depending upon which bit of code I place before the other (ARGH), but I can't get them to both work together on the page. What am I doing wrong?
I have a client that provides a .xls file on their site that we have no control over that we download the file and then read it to update inventory. The first column is the SKU and in cell A2 it has the value 1028. This outputs fine but when I get to A8 the value is '1051-LV' and in my output it is blank. I am thinking in my dataset it reads A2 value and that becomes the type for the remainder of the rows. But what if that is wrong? How do I fix so it doesn't set the datetype to say int when it could be a string type?
Below is my code and works but the output of certain rows sku values are blank and are not like that in the excel file.
Code: Protected Sub btnGetExcelFile_Click(sender As Object, e As System.EventArgs) Handles btnGetExcelFile.Click litOutput.Text = "" Dim ws As New WebPost ws.URL = "http://www.domain.com/dropship/feed.xls" 'downloads excel file based on url Dim bExcel() As Byte = ws.RequestBinaryData("", True)
If I need to fetch one whole column from Table1 in the DB, should I fetch it using datatable or dataset? I can do both ways. I mean ok I should use Datatable. Why is that? What would happen if I use Dataset? ok that's what I wanted to know. So there's memory issue. I mean whatever I use be it Datatable or Dataset, both will be fetching only ONE column frommy table in DB. How is Dateset's gonna use more memory then?