Get the checkbox value is checked or not using Jquery

 $(document).ready(function () {
    $('#<%=chkValidateBabyName.ClientID%>').change(function () {
          if ($(this).is(":checked")) {
            alert("Check box checked");
          }
          else{
           alert("Check box un checked");
         }
    });
});

Include this code in document ready function. then you will get checkbox value when the check box value is changed..

Select Values from sql table with auto generated Serial number

select ROW_NUMBER() OVER (order by Modified_On desc) as SerialNumber, Name from StudentDetails

How to create a static variable at client side

Actually we cant create a static variable at client side. But we can keep the value even after page postback using Hidden field control.

First we need to create a hidden control and need to set ClientIDMode as "Static"

Ex: <asp:HiddenField ID="hndControl" ClientIDMode="Static" runat="server" />

After that we need to assign the value to that hidden field.

document.getElementById('<%= hndControl.ClientID %>').value = "Static";

Here after we can use that value until we change hidden field value.

How to avoid alphabets and special character from text box using javascript

Use the following code OnKeyPress Event in your text box:

<asp:TextBox ID="txtNumber" runat="server" OnKeyPress="return IsNumeric(event);"></asp:TextBox>


function IsNumeric(e) {
    var keyCode = e.which ? e.which : e.keyCode
    var ret = ((keyCode >= 48 && keyCode <= 57) || specialKeys.indexOf(keyCode) != -1);
    document.getElementById("error").style.display = ret ? "none" : "inline";
    //TestOnTextChange();
    return ret;
}

Disable Copy, Cut and Paste options in text box

Include the following options in your text box:

onpaste="return false"
oncut="return false"
oncopy="return false"

it will avoid the cut, copy and paste options from your text box

DataTable does not contain definition for AsEnumerable

The method you want is in the System.Data namespace, so that using directive is fine, but you also need a reference to the System.Data.DataSetExtensions assembly.

Timer Job Issues

This is the most common error in timer job.

Keep your scope as site

  public override void FeatureActivated(SPFeatureReceiverProperties properties)

  {

            SPSite site = properties.Feature.Parent as SPSite;

}

get the site as mentioned above.

If still you get the same error please check your code whether you are using any custom dll.
Because timer job sometimes will not accept custom dll files. so try to avoid those.