What I learnt today

Couple of days ago, I was working on a project where I was supposed to convert SQL queries in LINQ. There was a simple SQL query as;

SELECT  * FROM Table1 td1LEFT
OUTER JOIN Table2ON 
td1.ColumnName = td2.ColumnName
WHERE td2.ColumnName IS NULL
ORDER BY SomeColumns

I ran this query in SQL Query analyzer, it returned me 100 records. And my converted LINQ code returned me 105 records. I converted this query intto LINQ to perform Left Outer Join as;
I did this in 2 ways;
Method 1:

var data= (from td1in Table1
           join td2 in Table2.Where(a => a.ColumnName == (int?)null) 
           on td1.ColumnName equals td2.ColumnName into outer
           from x in outer.DefaultIfEmpty()
           orderby SomeColumns
           select td1);

Method 2:

var data = from td1 in Table1
           join td2 in Table2
           on td1.ColumnName equals td2.ColumnName into outer
           from item in outer.DefaultIfEmpty()
           where item.ColumnName.Value == (int?)null
           orderby somecolumns
           select td1 ;

This gave me an exception as, failed to enumerate results

var data = from td1 in Table1
           join td2 in Table2
           on td1.ColumnName equals td2.ColumnName into outer
           from item in outer.DefaultIfEmpty()
           where item == null
           orderby somecolumns
           select td1 ;

In my original query that line item.ColumnName.Value == (int?)null was wrong, because I tried to retrieve value for all ColumnName even if item was null. I corrected that with the following query and it worked fine.

Classic mode (the only mode in IIS6 and below) is a mode where IIS only works with ISAPI extensions and ISAPI filters directly. In fact, in this mode, ASP.NET is just an ISAPI extension (aspnet_isapi.dll) and an ISAPI filter (aspnet_filter.dll). IIS just treats ASP.NET as an external plugin implemented in ISAPI and works with it like a black box (and only when it's needs to give out the request to ASP.NET). In this mode, ASP.NET is not much different from PHP or other technologies for IIS.

Integrated mode, on the other hand, is a new mode in IIS7 where IIS pipeline is tightly integrated (i.e. is just the same) as ASP.NET request pipeline. ASP.NET can see every request it wants to and manipulate things along the way. ASP.NET is no longer treated as an external plugin. It's completely blended and integrated in IIS. In this mode, ASP.NET HttpModules basically have nearly as much power as an ISAPI filter would have had and ASP.NET HttpHandlers can have nearly equivalent capability as an ISAPI extension could have. In this mode, ASP.NET is basically a part of IIS.

What I learnt today

Left outer join using LINQ - yields different outputs

Classic mode and Integrated mode in IIS

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