Как я могу использовать этот синтаксис sql для linq?

Question

SELECT t0.SHOPID, 
     t0.CONSGIPOS, 
     t1.StoreName as CStorename, 
     t0.ORDPOS, 
     t2.StoreName as OStoreName 
FROM EC_ORDER t0 
LEFT JOIN HIERARCHY t1 
    ON (t0.CONSGIPOS = t1.STOREID) 
LEFT OUTER JOIN HIERARCHY t2 
    ON (t2.STOREID = t0.ORDPOS) 

Answer 1

Использовать DefaultIfEmpty для левых соединений в LINQ. Попробуйте следующее:

var result = (from t0 in context.EC_ORDER 
       join t1 in context.HIERARCHY on t0.CONSGIPOS == t1.STOREID into t1tmp 
       from t1t in t1tmp.DefaultIfEmpty() 
       join t2 in context.HIERARCHY on t0.ORDPOS == t2.STOREID into t2tmp 
       from t2t in t2tmp.DefaultIfEmpty() 
       select { 
         t0.SHOPID, 
         t0.CONSGIPOS, 
         CStorename = t1t != null ? t1t.StoreName : null, 
         t0.ORDPOS, 
         OStoreName = t2t != null ? t2t.StoreName : null 
         }).ToList();