Linq SELECT AS和CONCAT

Question

我得到了一個SQL查詢，我需要將它轉換成LINQ，這不是問題，但在這個特定的查詢中有幾個項目需要幫助，那些是選擇列名稱作爲''，也是連接。這是有問題的查詢：

SELECT vessel_idx, 
     vessel_name, 
     spotlist_dp, 
     spotlist_bhp, 
     spotlist_deck, 
     spotlist_bp, 
     spotlist_oilrec, 
     spotlist_fifi, 
     spotlist_rov, 
     '' AS fixture_charterer, 
     '' AS fixture_work, 
CONCAT(fixture_charterer , 
     ' ', 
     mid(fixture_start,9,2), 
     '/', 
     mid(fixture_start,6,2)) AS next_charterer_info, 
     '' AS fixture_location, 
     '0000-00-00 00:00:00' AS fixture_stop, 
     '' AS fixture_note 
FROM tbl_vessels 

WHERE vessel_type='AHTS' 

AND current_location_spotlist_id = 2 
AND fixture_start > '2016-02-12 08:30:00' 
AND vessel_status = 'PPT' 

ORDER BY fixture_stop 

平常的東西一樣，並在等我可以對付它的purly這些部分我與掙扎。選擇列 ''：

SELECT '' AS fixture_charterer, 
     '' AS fixture_work, 

和concatination

CONCAT(fixture_charterer , 
     ' ', 
     mid(fixture_start,9,2), 
     '/', 
     mid(fixture_start,6,2)) AS next_charterer_info, 
     '' AS fixture_location, 
     '0000-00-00 00:00:00' AS fixture_stop, 
     '' AS fixture_note 

非常感謝

Answer 1

SELECT AS被表示爲：

var demo = from vessel in db.tbl_vessels 
     select new { 
      fixture_charterer = "", 
      fixture_work = "" 
     }; 

CONCAT是：

Answer 2

您可以選擇常量像""容易：

var q = from v in .... 
     .... 
     select new 
     { 
      ..., 
      fixture_charterer = "", 
      fixture_work = "", 
      next_charterer_info = 
       (v.fixture_charterer ?? "") + " " 
      + (v.fixture_start == null ? "" : v.fixture_start.Substring(8,2)) 
     };