Maybe something like this can get you started in the right direction. I made a mock database with similar columns based on your column names and got some results.
class Program
{
static AccountContextDataContext aContext = new AccountContextDataContext(@"Data Source=;Initial Catalog=;Integrated Security=True");
static LoanContextDataContext lContext = new LoanContextDataContext(@"Data Source=;Initial Catalog=;Integrated Security=True");
static void Main()
{
var query = from a in aContext.ACCOUNTs
join app in aContext.APPLICATIONs on a.GUID_ACCOUNT_ID equals app.GUID_ACCOUNT
where app.GUID_APPLICATION.ToString() == "24551D72-D4C2-428B-84BA-5837A25D8CF6"
select GetLoans(app.GUID_APPLICATION);
IEnumerable<LOAN> loan = query.First();
foreach (LOAN enumerable in loan)
{
Console.WriteLine(enumerable.GUID_LOAN);
}
Console.ReadLine();
}
private static IEnumerable<LOAN> GetLoans(Guid applicationGuid)
{
return (from l in lContext.LOANs where l.GUID_APPLICATION == applicationGuid select l).AsQueryable();
}
}
Hope this helps!