Question: I am curious to know why should a Database person learn LINQ. How can it be useful.

Answer: 
LINQ has one big advantage over most other data access methods: it centers around the '**query expression**' metaphor, meaning that queries can be passed around like objects and be altered and modified, all *before* they are executed (iterated). In practice what that means is that code can be modular and better isolated. The data access repository will return the 'orders' query, then an intermediate filter in the request processing pipeline will decorate this query with a filter, then it gets passed on to a display module that adds sorting and pagination etc. In the end, when its iterated, the expression has totally transformed into very specific `SELECT ... WHERE ... ORDER BY ... LIMIT ...` (or the other back-end specific pagination like ROW\_NUMBER). For application developers, this is priceless and there simply isn't any viable alternative. This is why I believe LINQ is here to stay and won't vanish in 2 years. It is definitely more than just a fad. And I'm specifically referring to LINQ as database access method. 

The advantage of manipulating query expression objects alone is enough of a factor to make LINQ a winning bid. Add to this the multiple container types it can manipulate (XML, arrays and collections, objects, SQL) and the uniform interface it exposes over all these disparate technologies, consider the parallel processing changes coming in .Net 4.0 that I'm sure will be integrated transparently into LINQ processing of arrays and collections, and is really no way LINQ will go away. Sure, today it sometimes produces unreadable, poorly performant and undebuggable SQL, and is every dedicated DBA nightmare. It will get better.
Is this a real question? It can't be answered with a code snippet. Most of these discussion type questions get closed quickly.