JQuery Basics

What is JQuery?
What does jQuery have to offer? First and foremost, jQuery has given me power over the Document Object Model (DOM)! jQuery Selectors are the greatest thing since sliced bread, no lie. Being able to EASILY find an object or group of objects in the DOM by ID, CSS Class, or by HTML Tag is something web developers have long needed.

To select an object from the DOM by ID would look like this:
$('#ID_Goes_Here')

To select an object from the DOM by CSS Class would look like this:
$('.CSS_Class_Name_Goes_Here')

To select an object from the DOM by HTML Tag would look like this:
$('Tag_Goes_Here')

For example, if I have a label that I want to be rendered but not visible I could create the label.

asp:label id="Label4" runat="server" cssclass="myLabel" text="This is " And later on in jQuery I can hide it like this.

$('#Label4').css('display', 'none');
It’s nice to be able to easily select an object and modify it, but what if you have a whole group of items you want to modify? With jQuery, you can EASILY loop through a collection of objects.

In this example I have a group of labels.

asp:label id="Label1" runat="server" cssclass="myLabel" text="This is "
asp:label id="Label2" runat="server" cssclass="myLabel" text="This is "
asp:label id="Label3" runat="server" cssclass="myLabel" text="This is "
asp:label id="Label4" runat="server" cssclass="myLabel" text="This is "
Now I want to update the text of each label to include its ID. I am going to loop through each object in the DOM with a CSS Class of .myLabel.

$('.myLabel').each(function() { $(this).append(this.id); });
What the jQuery code above does is execute a function that will append the object’s ID to its text value. Notice the Selector inside the function $(this). The syntax is used to find the loop’s current object in the DOM.

Now I have shown you some snippets here and there, let me show you what my page actually looks like.

script type="text/javascript"
function pageLoad() {
$('.myLabel').each(function() { $(this).append(this.id); });
$('.myLabel').css('color', '#FFFFFF').css('font-size', '30px');
$('#Label4').css('display', 'none');
$("#Panel1").html("(ul)(li)Item One(/li)(li)Item 2(/li)(/ul)");
}
script
asp:label id="Label1" runat="server" cssclass="myLabel" text="This is "

asp:label id="Label2" runat="server" cssclass="myLabel" text="This is "

asp:label id="Label3" runat="server" cssclass="myLabel" text="This is "

asp:label id="Label4" runat="server" cssclass="myLabel" text="This is "

asp:panel id="Panel1" runat="server"

Why we Use Triggers

Triggers can update, insert, or delete data in the same or other tables. This is useful to maintain relationships between data or to keep audit trail information.


Triggers can check data against values of data in the rest of the table or in other tables. This is useful when you cannot use RI constraints or check constraints because of references to data from other rows from this or other tables.



Triggers can use user-defined functions to activate non-database operations. This is useful, for example, for issuing alerts or updating information outside the database.


Some Examples:


INSERT INTO Customers

VALUES (Sheeban,Ahmed,Memon,Karachi,
Sindh,110016,01126853138)

INSERT INTO Customers

VALUES(Faizan,Ahmed,Khanani,

Chicago,illions,326541,9412658745)


INSERT INTO Products

VALUES (ASP.Net Microsoft Press,550)
INSERT INTO Products

VALUES (ASP.Net Wrox Publication,435)
INSERT INTO Products

VALUES (ASP.Net Unleased,320)
INSERT INTO Products

VALUES (ASP.Net aPress,450)


CREATE TRIGGER invUpdate ON [Orders]

FOR INSERT

AS

UPDATE p SET p.instock=[p.instock,i.qty]

FROM products p JOIN inserted I ON p.prodid = i.prodid


CREATE TRIGGER SindhDel ON [Customers]

FOR DELETE

AS

IF (SELECT state FROM deleted) = Sindh

BEGIN

PRINT Can not remove customers from Sindh

PRINT Transaction has been canceled

ROLLBACK

END


CREATE TRIGGER CheckStock ON [Products]

FOR UPDATE

AS

IF (SELECT InStock FROM inserted) < 0

BEGIN

PRINT Cannot oversell Products

PRINT Transaction has been cancelled

ROLLBACK

END