Question

我使用linq来查询来自数据库的反向记录的sql查询。我使用查询来绑定gridview。

   protected void grdBind()
        {
            try
            {
                EventManagerDataContext db = new EventManagerDataContext();


                var z = (from x in db.EMR_EVENTs
                         join y in db.EMR_CLIENTs on x.ClientID equals y.ClientID
                         where y.ClientID==x.EventID
                         select x.EventID).Count();



                var q = from a in db.EMR_CLIENTs
                        join b in db.EMR_EVENTs on a.ClientID equals b.ClientID     
                        join c in db.EMR_ACCOUNTs on a.ClientID equals c.ClientID
                        join d in db.EMR_SUBSCRIPTIONs on c.Account_ID equals d.Account_ID
                        join f in db.EMR_SUBSCRIPTION_KINDs on d.Subscription_kind_ID equals f.Subscription_kind_ID


                        select new
                        {
                            Customer = a.Name,
                            Events = z,
                            TurnOver = f.Monthly_Fee,
                            StartDate = d.Start_Date,
                            EndDate = d.End_Date,
                            CreteDate = d.Create_Date,
                            ClientID = a.ClientID,
                            EventID = b.EventID,
                            SubscriptionID = d.Subscription_ID,
                            Subscription_kind_ID=f.Subscription_kind_ID,
                            Account_ID=c.Account_ID,
                        };



                 grid.DataSource = q.ToList();
                 grid.PageSize = int.Parse(drpPageSize.SelectedValue);
                 grid.DataBind();


            }
            catch
            {

                throw;
            }
        }

我收到了这个输出，

enter image description here

我收到此查询的输出，但我不想要此输出，我想要这样的输出。

客户名称 活动

ketan 18

monika 12

和其他记录等等意味着我在这里收到9次客户名称并且他创建了事件，但我只想要一些事件和客户名称

意味着我只想要一个客户端名称和事件总数，我是linq to sql的新手。那么代码中的变化是什么？？

Answer 1

当您在查询中使用连接语法时，您不需要使用'where' 然后将您的查询更改为：

 var z = (from x in db.EMR_EVENTs
                     join y in db.EMR_CLIENTs on x.ClientID equals y.ClientID
                     select x.EventID).Count();

Answer 2

我找到了解决方案。here

也可以使用。useful link

这是我的解决方案。

 EventManagerDataContext db = new EventManagerDataContext();



                var q = from a in db.EMR_CLIENTs
                        join b in db.EMR_EVENTs on a.ClientID equals b.ClientID into z                       
                        join c in db.EMR_ACCOUNTs on a.ClientID equals c.ClientID
                        join d in db.EMR_SUBSCRIPTIONs on c.Account_ID equals d.Account_ID
                        join f in db.EMR_SUBSCRIPTION_KINDs on d.Subscription_kind_ID equals f.Subscription_kind_ID


                        select new
                        {
                            Customer = a.Name,
                            Events =z.Where(b =>b.ClientID==a.ClientID).Count(),                         
                            TurnOver = f.Monthly_Fee,
                            StartDate = d.Start_Date,
                            EndDate = d.End_Date,
                            CreteDate = d.Create_Date,
                            ClientID = a.ClientID,
                            SubscriptionID = d.Subscription_ID,
                            Subscription_kind_ID=f.Subscription_kind_ID,
                            Account_ID=c.Account_ID,
                        };



                 grid.DataSource = q.ToList();

使用linq到sql计数结果记录

2 个答案: