重新使用基於布爾值LINQ查詢

Question

我試圖寫一個單一的查詢，其中將包括的兩個條件之一，基於輸入變量：

!(from o in db.Products.Where(x => x.Company_ID == cid && x.IsDeleted != true) 

或

(from o in db.Products.Where(x => x.Company_ID == cid && x.IsDeleted != true) 

我現在的方法，覆蓋前一個條件，如下所示。我已經包含productExists，它將成爲決定我是否希望從上面獲得條件＃1或＃2的參數。

public IQueryable<ProductImportViewModel> AllImports(int id, bool productExists) 
{ 
    return (from t1 in db.Products_Staging 
      where (t1.ImportFileId == id) && !(from o in db.Products.Where(x => x.Company_ID == cid && x.IsDeleted != true) 
               select o.ProductName).Contains(t1.ProductName) 
      select new ProductImportViewModel 
      { 
       Id = t1.Id 
      } 
} 

如果有人能幫助我，我會非常感激。

Answer 1

事情是這樣的，也許：

where (t1.ImportFileId == id) && 
      (
       productExists==true 
       && 
       !(from o in db.Products.Where(x => x.Company_ID == cid && x.IsDeleted != true). 
               Select(o=> o.ProductName).Contains(t1.ProductName) 
      ) 
      || 
      (
       productExists==false 
       && 
       (from o in db.Products.Where(x => x.Company_ID == cid && x.IsDeleted != true). 
               Select(o=> o.ProductName).Contains(t1.ProductName) 
      ) 

你也可以做這樣的事情：

var query=(from o in db.Products 
      .Where(x => x.Company_ID == cid && x.IsDeleted != true). 
      Select(o=> o.ProductName); 
------ 
where (t1.ImportFileId == id) && 
    (
     productExists && !query.Contains(t1.ProductName) 
    ) 
    || 
    (
     !productExists && query.Contains(t1.ProductName) 
    ) 

兩個查詢會導致在同一個SQL