I like that there is a “Compare” function right out-of-the-box in Visual Studio, and even though many regular developers will choose to download a third-party application for the job, it’s perfectly fine for me.
Two problems: First off, I couldn’t find a straightforward way to open “compare” in the Visual Studio IDE without right-clicking an existing item in a source control repository. And second, wouldn’t it be cool if we could put a shortcut to it on the Windows “Send to” context menu?
Do you ever compare the values of a lot of columns in two tables? Sure you do. Like, for instance, in a cross update, when you need to figure out which rows you should actually update. But it gets worse if the columns are nullable. The fact that any value could potentially be NULL vastly complicates the comparison and might wreak havoc not only on your code but also on your query performance.
But there’s hope.
NULL is an undefined value and as such, it has a special status as values and datatypes go in SQL Server. There are quite a few potential pitfalls to watch out for when you’re dealing with data that can contain NULL values.
sqlsunday.com 