Question

I have a particular function which checks if a particular row matches the query condition.If it does then I retrieve the value and store it in my variable , if it doesnot have a value I insert it.However I have a try{} catch{} block which determines if it exists or not.If it goes inside a catch block , I call a function which will insert a record in that table , I would like to know is this approach good ,Calling a function inside a catch block , is it ok, what are the alternatives to find out if my query returns a result or not.Here is my code

public void CheckApplicationNo(string TableName,string BranchNo)
    {
        try
        {
            var appno = (from app in dt.sys_Keys
                         where app.TableName == TableName && app.BranchNo.ToString() == BranchNo
                         select app.NewValue).Single();

                Global.ApplicationNo = appno.ToString();
                UpdateApplicationNo("Data_Customer_Log", Global.BranchNo);
        }

        catch (Exception ex)
        {

            InsertApplicationNo(); 
        }


    }

Any suggestons are welcome.
Thanks.

Answer 1

You should use .SingleOrDefault()

select app.NewValue).SingleOrDefault(); 

    if (appno == null)
    {
      InsertApplicationNo();  
    }
    else
    {
     ..
    }

It returns null if there are no results.