Kushan Perera

class Program
{

static void Main(string[] args)
{
//Collection
var primes = new List<int> { 1, 2, 3, 5, 7, 11, 13, 17, 19, 23 };

//SQL like quering
IEnumerable<int> query = from val in primes
where val < 13
select val;

foreach (var val in query)
Console.WriteLine(val);

//using expressions
var methodQuery = primes.Where(x => x < 13);

foreach (var val in methodQuery)
Console.WriteLine(val);

}
}

}
}

Extracting data from source systems and bringing it into the data warehouse is commonly called ETL (Extract-Transform-Load)



Methodlogy can be vary but the process remains same



Usually all the three phases execute in parallel since the data extraction takes time, so while the data is being pulled another transformation process executes, processing the already received data and prepares the data for loading and as soon as there is some data ready to be loaded into the target, the data loading kicks off without waiting for the completion of the previous phases.(Wiki, 2015)

References

http://docs.oracle.com/cd/B19306_01/server.102/b14223/ettover.htm

http://en.wikipedia.org/wiki/Extract,_transform,_load