LINQ left join with only the row having maximum value of a column

You can do it many ways. One of those way is:

var result = (from pi in projectInformations              join pu in projectUpdates on pi.ProjectID equals pu.ProjectID into tpu              from t in tpu.OrderByDescending(c => c.CreateDate).Take(1)              select new { pi.ProjectID, pi.DataA, t.CreateDate, t.DataB }).ToList();

You can use a one to many association from ProjectInformation to ProjectUpdate and OrderByDescending/FirstOrDefault.

public class ProjectInformation {  public int ProjectID { get; set; }  public virtual ICollection<ProjectUpdate> ProjectUpdates { get; set; }}db.Project  .Select(p => new {    ProjectID = p.ProjectID,    MostRecentProjectUpdate = p.ProjectUpdates.OrderByDescending(u => u.CreateDate).FirstOrDefault()});

Note: Using OrderByDescending may be tricky if CreateDate is a string rather than a Date in your database.

Try this:-

var result = (from pi in projectInfo              join pu in projectupdates              on pi.ProjectID equals pu.ProjectID into g              let data = g.OrderByDescending(x => DateTime.ParseExact(x.CreateDate,                            "dd/M/yyyy", CultureInfo.InvariantCulture)).FirstOrDefault()              select new              {                  ProjectID = data.ProjectID,                  CreatedDate = data.CreateDate,                  DataA = pi.DataA,                  DataB = data.DataB               }).ToList();

Working Fiddle.

Please note, Since I am using FirstOrDefault you need to check if data is not null before accessing its properties.