Question

I’m trying to recreate some SQL queries I have into L2E statements. One of the queries is:

SELECT TOP 25 itms.[StringValue]
      ,itms.[Name]
      ,itms.[Picture]
  FROM [DB].[dbo].[Items] AS itms
  WHERE itms.StringValue LIKE '[A-G]%'

I am given a start char (A in this case) and an end char (G) and I need to pull all of the items whos StringValue starts with a char between Start and Finish.

My first try was to see if L2E would just give it to me with this query:

items = from i in items
        where i.StringValue.StartsWith("[" + refinement.Value + "]")
        select i;

I figured it wouldn’t work, but it was worth a try.

Answer 1

Couple of options that should work:

1) if you know the filter is just based on the first char, then you could do something like:

var startChar = 'A';
var endChar = 'G';

// other options, but you get the point
var validStartChars = Enumerable.Range(0, 26)
    .Select(i => (char)('A' + i))
    .Where(c => c >= startChar && c <= endChar)
    .ToArray();

var matches = items.Where(i => validStartChars.Contains(i.StringValue[0]));

similarly, you could fetch the first char and just do the greater/lesser checks in the Where clause (if it’s always a range like that)

2) if you want, you can still use sql to query with L2E, just use the ExecuteStoreQuery and let it return the entities back for you:

http://msdn.microsoft.com/en-us/library/dd487208.aspx

If you want the returned entities to be tracked, make sure to call the overload that lets you specify the entity set name:

http://msdn.microsoft.com/en-us/library/dd487226.aspx