Come-at-able

I pretty new to LINQ, and I’m keen to get more experience using it, so whenever an opportunity arises I like to try writing LINQ queries. I needed to write a method to extract a comma separated list of numbers from a config file, and return this as List. I was looking at ways to do this using LINQ, but hit a problem. I wanted my LINQ query to filter out any values in the CSV string that could not be parsed as an int, without causing an exception. Using int.TryParse() seemed like a possible solution, but I had problems because the TryParse() method has an out parameter to store the parsed result. I ended up with the code below, which seems to work, but looks very messy, because I think it is parsing the string twice. public static List<int> AuthorisedGroups { get       {             string[] authorisedGroupsStr = ConfigurationManager.AppSettings["AuthorisedGroups"].Split(new char[] { ...

In SQL so many times we need to filter value from one table when the values are not exist on other table. As Below SELECT    GroupID ,    GroupName ,    GroupNumber      FROM  TableA     WHERE  GroupID NOT IN ( SELECT GroupID FROM TableB )   You can do it as below: return   from c in  context . TableA where !db. context . TableB .Any(p => p.GroupID== c.GroupID) select c;

In SQL so many times we need to filter value from one table when the values are exist on other table. As Below SELECT    GroupID ,    GroupName ,    GroupNumber ,   FROM    TableA  WHERE    GroupID IN ( SELECT GroupID FROM TableB )   You can do it as below:  var temp = context . TableA           . Where ( x => context . TableB . Any ( y => y . GroupID != x . GroupID ))           . Select ( x => new { GroupID = x . GroupID , GroupName = x . GroupName , GroupNumber = x . GroupNumber }). ToList (); or return DomainContext.TableA.Where(a => DomainContext.TableB.Any(b => b.GroupId == a.GroupId))

In LINQ every join you made is by default Inner Join. To perform the Left Outer Join you can do like below: from mem in ctx.Member join dist in ctx.District on mem.district_id equals dist.district_id into jointDist from dist in jointDist.DefaultIfEmpty() select new StagingClass {  member_id = mem.member_id,  district_name = dist.district_name }

In LINQ if you want to show the child table single record with the parent table, you can do like below: from mem in ctx.Member join ord in ctx.MemOrder on mem.member_id equals ord.member_id into memord select new StagingClass {  mem.member_id,  latestOrderNo = memord.FirstOrDefault().OrderNo }