c# - Linq 查询无法合并两个表记录

Question

我正在尝试使用 Concat 合并两个 linq 查询。但是当我编译查询时，我收到两个错误。

IQueryable”不包含“Concat”的定义，并且最佳扩展方法重载“ParallelEnumerable.Concat(ParallelQuery, IEnumerable)”需要“ParallelQuery”类型的接收器

第二个错误是方法所有代码未返回所有路径值

这是我的界面。

[OperationContract]
        [WebInvoke(Method = "GET",
    RequestFormat = WebMessageFormat.Json,
    ResponseFormat = WebMessageFormat.Json,
     //BodyStyle = WebMessageBodyStyle.Bare,
     UriTemplate = "/TranscationDetails/{Account_Number}")]
        string TranscationDetails(string Account_Number);

这是实现。

  public string TranscationDetails(string Account_Number)
        {

            using (HalifaxDatabaseEntities context = new HalifaxDatabaseEntities())
            {

                var DepositQuery = from x in context.Current_Account_Deposit
                                   where x.Account_Number == Convert.ToInt32(Account_Number)
                                   select x;

                var WithdrawQuery = from x in context.Current_Account_Withdraw
                                    where x.Account_Number == Convert.ToInt32(Account_Number)
                                    select x;

                var merge = DepositQuery.Concat(WithdrawQuery);//**Error on this line**


            }

        }  

Answer 1

您不需要使用 2 个单独的查询，只需通过连接 2 个表构建单个查询并从结果集中选择所有必需的属性即可。然后，您可以将其放入 IEnumerable 对象中并使用 JSON serializer从查询结果返回 JSON 响应:

public string TranscationDetails(string Account_Number)
{
     using (HalifaxDatabaseEntities context = new HalifaxDatabaseEntities())
     {
         var CombinedQuery = (from x in context.Current_Account_Deposit
                             join y in context.Current_Account_Withdraw
                             on x.Account_Number equals y.Account_Number
                             where x.Account_Number == Convert.ToInt32(Account_Number)
                             select new { 
                                x.Account_Number,
                                // put other properties here 
                             }).ToList();

         var js = new System.Web.Script.Serialization.JavaScriptSerializer();

         return js.Serialize(CombinedQuery); // return JSON string
     }
}