c#-Linq查询返回记录列表,而不是显示单个记录

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我试图发展银行系统.我试图将三个表的记录连接到单个表中.但是问题是当我编译它时,出现以下错误.

Error CS1929 ‘IOrderedQueryable<>’ does not contain
a definition for ‘Concat’ and the best extension method overload
‘ParallelEnumerable.Concat<>(ParallelQuery<>, IEnumerable<>)’ requires a
receiver of type ‘ParallelQuery<>

这是我的Linq查询.

  public string TranscationDetails(string Account_Number)
            {

                var accountNumber = int.Parse(Account_Number);//It could be better to use TryParse
                using (HalifaxDatabaseEntities context = new HalifaxDatabaseEntities())
                {

        var inOut = context.Current_Account_Deposit.Where(x => x.Account_Number == accountNumber).Select(w => new
                {
                    w.Account_Number,
                    Deposit = (decimal?)null,
                    Withdrawal = (decimal?)w.Amount,
                    w.Date
                }).Concat(context.Current_Account_Withdraw.Select(d => new
                {
                    d.Account_Number,
                    Deposit = (decimal?)d.Amount,
                    Withdrawal = (decimal?)null,
                    d.Date
                })).OrderBy(r => r.Date)
             .Concat(context.Current_Account_Details.Select(e => new
             {
                 //You should perform same anonymous type which you want to concat
                 Account_Number = e.Account_Number,
                 Deposit = (decimal?)e.Account_Balance,
                 Withdrawal = (decimal?)null,
                e.Account_Fees
             }));


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

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

这是DBContext类.

  public partial class HalifaxDatabaseEntities : DbContext
        {
            public HalifaxDatabaseEntities()
                : base("name=HalifaxDatabaseEntities")
            {
            }

            protected override void OnModelCreating(DbModelBuilder modelBuilder)
            {
                throw new UnintentionalCodeFirstException();
            }

            public virtual DbSet<Web_User_login> Web_User_login { get; set; }
            public virtual DbSet<USER> USERS { get; set; }
            public virtual DbSet<tblUser> tblUsers { get; set; }
            public virtual DbSet<Current_Account_Holder_Details> Current_Account_Holder_Details { get; set; }
            public virtual DbSet<Current_Account_Details> Current_Account_Details { get; set; }
            public virtual DbSet<Current_Account_Deposit> Current_Account_Deposit { get; set; }
            public virtual DbSet<Current_Account_Withdraw> Current_Account_Withdraw { get; set; }
        }

这是模型类..

这是数据库记录

这是我期望的结果,当我单击帐号时,它应该显示特定记录

解决方法:

您只能在本地Concat.尝试在每个Concat之前添加.ToList(),以便在连接之前在本地实现记录.

注意：您的Where子句仅适用于Current_Account_Deposit.提取和详细信息将返回所有记录.

尝试生成3个基本上下文查询.每个表一个,并使用ToList()完成每个表.稍后,使用Concat将所有3个列表连接为一个列表.

这将使您理解概念,并可以从这里继续前进.

var q1 = context.Current_Account_Deposit.Where(x => x.Account_Number == accountNumber).Select(w => new
    {
        w.Account_Number,
        Deposit = (decimal?)null,
        Withdrawal = (decimal?)w.Amount,
        w.Date
    }).ToList();

    var q2 = context.Current_Account_Withdraw.Select(d => new
    {
        d.Account_Number,
        Deposit = (decimal?)d.Amount,
        Withdrawal = (decimal?)null,
        d.Date
    }).OrderBy(r => r.Date).ToList();

    var q3 = context.Current_Account_Details.Select(e => new
         {
             //You should perform same anonymous type which you want to concat
             Account_Number = e.Account_Number,
             Deposit = (decimal?)e.Account_Balance,
             Withdrawal = (decimal?)null,
             e.Account_Fees
         }).ToList();

    var inOut = q1.Concat(q2).Concat(q3).ToList();

您可能需要向q2和Q3添加相同的Where子句.我不确定你是否想要那样.

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