Quick Reference to ADO.Net

	Command Objects	Returns	O/p Type	Used
1	Execute Non Query	No Of Rows Effected	int	Insert, Update
2	ExecuteReader	SqlDataReader	SqlDataReader	Fetch Data
3	ExecuteScalar	First Col of  First Row	int, string	Count(*)
4	SqlDataReader
	Features
	Forward Read-only
	Initiate only using ExecuteReader()
5	Dataset
	The DataSet represents a complete set of data independent of actual DataSource
	Interaction with existing data sources is controlled through the DataAdapter

SQL Server Data Types and Their .NET Framework Equivalents

SQLServer datatype       CLRdatatype(SQLServer)    CLRdatatype(.NET Framework)  
varbinary                     SqlBytes, SqlBinary           Byte[]  
binary                        SqlBytes, SqlBinary           Byte[]  
varbinary(1), binary(1)       SqlBytes, SqlBinary           byte, Byte[] 
image                         None                          None

varchar                       None                          None
char                          None                          None
nvarchar(1), nchar(1)         SqlChars, SqlString           Char, String, Char[]     
nvarchar                      SqlChars, SqlString           String, Char[] 
nchar                         SqlChars, SqlString           String, Char[] 
text                          None                          None
ntext                         None                          None

uniqueidentifier              SqlGuid                       Guid 
rowversion                    None                          Byte[]  
bit                           SqlBoolean                    Boolean 
tinyint                       SqlByte                       Byte 
smallint                      SqlInt16                      Int16  
int                           SqlInt32                      Int32  
bigint                        SqlInt64                      Int64 

smallmoney                    SqlMoney                      Decimal  
money                         SqlMoney                      Decimal  
numeric                       SqlDecimal                    Decimal  
decimal                       SqlDecimal                    Decimal  
real                          SqlSingle                     Single  
float                         SqlDouble                     Double  

smalldatetime                 SqlDateTime                   DateTime  
datetime                      SqlDateTime                   DateTime 

sql_variant                   None                          Object  
User-defined type(UDT)        None                          user-defined type     
table                         None                          None 
cursor                        None                          None
timestamp                     None                          None 
xml                           SqlXml                        None

Get Assembly location of the DLL added to SQL Server

SELECT 
    assembly = a.name, 
    path     = f.name
FROM sys.assemblies AS a
INNER JOIN sys.assembly_files AS f
ON a.assembly_id = f.assembly_id
WHERE a.is_user_defined = 1;

Get GridView Column Headers and Appropriate Row Values in Asp.Net

Get Gridview column header(s) text and Specific Row's Values on Row Command in asp.net. Below Method takes GridView control, Command Source Within the Row(LinkButton, Button, ImageButton, etc..), no of Columns to skip in from Start Column and from End Column as Parameters and returns List<KeyValuePair<headerText,Values>> as output.

private void SetDeleteDetails(GridView pGV, object pCmdSource, int pStartSkipColCount=0, int pEndSkipColCount=0)

        {

            List<KeyValuePair<string, string>> lkvp = new List<KeyValuePair<string, string>>();

            GridViewRow rw = (GridViewRow)((Control)pCmdSource).NamingContainer;

            for (int i = pStartSkipColCount; i < pGV.Columns.Count - pEndSkipColCount; i++)

                if (!string.IsNullOrEmpty(rw.Cells[i].Text))

                    lkvp.Add(new KeyValuePair<string, string>(pGV.Columns[i].HeaderText, rw.Cells[i].Text));

            //Session["DeleteDetails"] = lkvp;

        }

Get Specific Property Name Using Expression

Hope the program explains all:

class Program
    {
        static void Main(string[] args)
        {
            SomeClass sc = new SomeClass();
            Console.WriteLine(sc.p1.GetType());

            //RemoteMgr.ExposeProperty(() => SomeClass.SomeProperty);
            MemberInfo member = RemoteMgr.GetMemberInfo((SomeClass p) => p.SomeProperty);
            Console.WriteLine(member.Name);
            Console.ReadKey();
        }
    }

    public class SomeClass
    {
        public string SomeProperty
        {
            get { return "Foo"; }
        }
    }

    public class RemoteMgr
    {
        public static MemberInfo GetMemberInfo<T, U>(Expression<Func<T,U>> expression)
        {
            var member = expression.Body as MemberExpression;
            if (member != null)
                return member.Member;
            throw new ArgumentException("Expression is not a member access", "expression");
        }
    }

Raising a Button Click Event Programmatically

You can use the following C# code raise the event:

((IPostBackEventHandler)Button1).RaisePostBackEvent(null);

This code will raise the button-click event for Button1 just as though the user clicked the button.  Since we are passing a null as the EventArgs for the event, the registered methods must not attempt to do anything with it.  Or, you could create an EventArgs object and pass it.

There is at least one other approach using reflection, but I think the technique above is the cleaner way to do this. 

Ref : http://www.netsplore.com/PublicPortal/Blog/tabid/284/EntryID/11/Default.aspx

Understanding ASP.NET View State

Introduction

Microsoft® ASP.NET view state, in a nutshell, is the technique used by an ASP.NET Web page to persist changes to the state of a Web Form across postbacks. In my experiences as a trainer and consultant, view state has caused the most confusion among ASP.NET developers. When creating custom server controls or doing more advanced page techniques, not having a solid grasp of what view state is and how it works can come back to bite you. Web designers who are focused on creating low-bandwidth, streamlined pages oftentimes find themselves frustrated with view state, as well. The view state of a page is, by default, placed in a hidden form field named __VIEWSTATE. This hidden form field can easily get very large, on the order of tens of kilobytes. Not only does the __VIEWSTATE form field cause slower downloads, but, whenever the user posts back the Web page, the contents of this hidden form field must be posted back in the HTTP request, thereby lengthening the request time, as well.

This article aims to be an in-depth examination of the ASP.NET view state. We'll look at exactly what view state is storing, and how the view state is serialized to the hidden form field and deserialized back on postback. We'll also discuss techniques for reducing the bandwidth required by the view state.

Note   This article is geared toward the ASP.NET page developer rather than the ASP.NET server control developer. This article therefore does not include a discussion on how a control developer would implement saving state. For an in-depth discussion on that issue, refer to the book Developing Microsoft ASP.NET Server Controls and Components.

Before we can dive into our examination of view state, it is important that we first take a quick moment to discuss the ASP.NET page life cycle. That is, what exactly happens when a request comes in from a browser for an ASP.NET Web page? We'll step through this process in the next section.

Source : http://msdn.microsoft.com/en-us/library/ms972976.aspx