Disable caching (Browser back button problem)

When the user hit the back button a locally cached copy of the previous page is retrieved without notifying the server. As a result the Info is out of sync.

Solution 1 --> Disable caching (do not work for all browsers)

Code to disable caching (to be executed everytime thepage is loaded)

Response.Cache.SetCacheability(HttpCacheability.NoCache);

Response.Cache.SetExpires(Now.AddSeconds(-1));   //--- (-1) means the page already expired

Response.Cache.SetNoStore();  //--tell the page not to cache the page

Response.AppendHeader("Pragma", "no-cache");  //---adds a header to the HTTP response object

Solution 2 --> Use timestamps or random numbers to track pages and detect when a page is current

Copy table into new temporary table and put data back in original table

Sometimes you need to modify a table, like add a new column when there are constrains in place and you may be asked to drop the table before you can modify it. One solution is to store data in a temporary table, make the change and place the data back.

This example works when you have an identity column (autoId)

--- (1)Create new table (TempTable1) and insert into this table using SELECT INSERT
SELECT *
INTO TempTable1
FROM Table1

--- (2)Modify the Table1 --> add columns etc

--- (3)Copy the data from TempTable1 to the original Table1
---    It is important to list all the fields but the autoId (if there is one)

INSERT INTO Table1 (col1,col2,....colN)
SELECT col1,col2,....,colN
FROM TempTable1

New Ajax Control Toolkit Features

DATE RANGE was added (Sept. 2011). When Using the Calendar Extender, you can specify startDate and endDate, and the user can pick a date within that range.

TWITTER control

 <asp:Twitter ID="Twitter1" runat="server"  Mode="Profile" ScreenName="MyTwitterName"/>

GRAVATAR

         <ajaxToolkit:Gravatar runat="server"

            Email="myEmail@myEmail.com"

            Size="200"

            Rating="R"

            DefaultImageBehavior="Identicon"

            DefaultImage="PathToMyImage" />

Sample of COALESCE in SQL SERVER

DECLARE @List nvarchar(100)
select @List= COALESCE(@List + ',', '') + colValue  from TableFields where categoryId = 15 and LOWER(name) <> 'subject'
select @List

This will return a concatenated string with all the values (in all rows) for the column colValue and categoryId = 15. (the categoryId could be a parameter  @categoryId)

String to Date in VB.NET

Here is a simple sample to parse from string to date and then to an specific format like yyyyMMdd,
which could be handy for file naming.

 Dim strDate As String = dateExpiration.Text
 Dim parsedDate As Date

 parsedDate = DateTime.Parse(strDate)
 txtMsg.Text = parsedDate.ToString("yyyyMMdd")

Pad a string with zeros on the left/right in C# until completing n digits

Very simple way to pad with zeros until completing n digits

           

strMyString.PadLeft(n,'0');

Sample

string strMyString = "1234";

strMyString = strMyString.PadLeft(7,'0');

...will display "0001234"

Other notes: there is a .PadRight() function too.

Kill an Excel process in C#

foreach (System.Diagnostics.Process process in System.Diagnostics.Process.GetProcessesByName("EXCEL"))

        {

            if (process.MainModule.ModuleName.ToUpper().Equals("EXCEL.EXE"))

            {

                process.Kill();

                break;

            }

        }