Linq to ASP.Net MVC 4中的Sql返回实际的查询字符串

Question

I am trying to get the First and Last Name string values out of my AspNetUsers table for a particuler record (ID). When I use Linq to Sql, it returns the entire sql query string. here is my code:

 var user = User.Identity.GetUserId();
            var currentUser = from aspNetUser in db.AspNetUsers
                              where aspNetUser.Id == user
                              select aspNetUser.FirstName + " " + aspNetUser.LastName;

I am trying to populate my User Textbox in my View with the Current Users First and Last Name. Which I have added as columns to the AspNetUsers Table. Why does it return this ugly query and not someone's first and last name?

it's returning this:

SELECT     CASE WHEN ([Extent1].[FirstName] IS NULL) THEN N'' ELSE [Extent1].[FirstName] END + N' ' + CASE WHEN ([Extent1].[LastName] IS NULL) THEN N'' ELSE [Extent1].[LastName] END AS [C1]    FROM [dbo].[AspNetUsers] AS [Extent1]    WHERE [Extent1].[Id] = @p__linq__0

Answer 1

Not really sure how you are getting the SQL query back, but you need a single record back from your query. Use First/FirstOrDefault like:

var currentUser = (from aspNetUser in db.AspNetUsers
                  where aspNetUser.Id == user
                  select aspNetUser.FirstName + " " + aspNetUser.LastName)
                  .FirstOrDefault();

FirstOrDefault would return the first record returned from the result. If there are no records then you will get null back.

You can also use Single \\ SingleOrDefault , since you are querying against ID and there should always be a single record returned. But both of them could throw an exception if there are multiple records matching your criteria. Use any of them according to your requirement.

Answer 2

you can use FirstOrDefault() to get single record against specific criteria:

var currentUser = db.AspNetUsers.FirstOrDefault(x=>x.Id == user);

var Name = currentUser.FirstName + " " + currentUser.LastName;