Update Table Query to Update Data From Another Table
Suppose we have two tables names Tbl_Topics & Tbl_TeacherTopics having columns MyTopic, TopicId, TopicName & TeacherTopicID, TopicId, TopicName respectively. now we want to update Tbl_Topics Table with data from Tbl_TeacherTopics for given TeacherTopicID
Query for the above statements is:
UPDATE Tbl_Topics SET TopicID=TT.TopicID,TopicName=TT.TopicName FROM
(SELECT TopicID,TopicName FROM Tbl_TeacherTopics WHERE TeacherTopicID=1062)
AS TT WHERE Tbl_Topics.MyTopic='Lakhan Pal garg'
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Java Script Event Handling
Code to handle event with javaScript.
Sample Code:
var pageMgr = Sys.WebForms.PageRequestManager.getInstance();
pageMgr.add_beginRequest(BeforeAjaxRequest);
pageMgr.add_pageLoaded(pageLoadedHandler);
var postbackElement;
function BeforeAjaxRequest(sender,args)
{
postbackElement=args.get_postBackElement();
if (postbackElement.id.indexOf("{ID of the Control}") != "-1")
{
/* Write your Code Here */
}
}
function pageLoadedHandler(sender,args)
{
if (typeof(postbackElement) == "undefined")
{
return;
}
else if (postbackElement.id.indexOf("{ID of the Control}") != "-1")
{
/* Write your Code Here */
}
}
You are having a asp link button with id lnkTest now according to this your above code should be:
var pageMgr = Sys.WebForms.PageRequestManager.getInstance();
pageMgr.add_beginRequest(BeforeAjaxRequest);
pageMgr.add_pageLoaded(pageLoadedHandler);
var postbackElement;
function BeforeAjaxRequest(sender, args)
{
postbackElement=args.get_postBackElement();
if (postbackElement.id.indexOf("lnkTest") != "-1")
{
alert("Before Ajax Request");
}
}
function pageLoadedHandler(sender, args)
{
if (typeof(postbackElement) == "undefined")
{
return;
}
else if (postbackElement.id.indexOf("lnkTest") != "-1")
{
alert("After Ajax the Request");
}
}
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string v/s StringBuilder
System.Text.StringBuilder strTest=new System.Text.StringBuilder();
Strings are immutable. immutable means every time we alter the string a new object is created. hence lower the performance. while stringBuilder are mutable. so it increase the performance where we need to perform altered, insert and remove operations. But it is not recommended to use StringBuilder always. for small string where you need to perform less operation then use string and in case of large string and more operation use StringBuilder.
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ref v/s out Parametes in C#
out and ref looks quite similar in nature.Both parameters are used to return back
some value to the caller of the function. But still there is a important difference
between them. these two types are used for specific purpose. When we use the out
parameter, The program calling the function need not assign a value to the out parameter
before making the call to the function. The value of the out parameter has to be
set by the function before returning the value.
For a ref type parameter, the value
to the parameter has to be assigned before calling the function. If we do not assign
the value before calling the function we will get a compiler error. Another important
thing to note here is that in case of ref parameter, the value passed by the caller
function can be very well used by the called function. The called function does
not have the compulsion to assign the value to a ref type parameter. But in case
of the out parameter, the called function has to assign a value.
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