Question

我有两个表，提交和记谱。 提交内容包含单个条目，符号包含通过 AppID 链接的提交内容的多个条目。

我试图完成的是提取给定日期范围的提交，以及最近的提交。

我已设法获取所有数据;但是，它为每个提交记录复制了每个提交记录。

这是我目前的代码。任何人都可以帮我解决这个问题吗？

 var query = (from s in db.Submissions
             from n in db.notations
             from d in db.DCodes
             where s.AppID == (int) n.AppID
             && s.DCode == d.DCode1
             && s.received >= dts
             && s.received <= dte
             select new ApplicationTrackingSystem.customModels.Export
             {
                 AppID = s.AppID,
                 received = s.received,
                 //dcode = s.DCode, 
                 dcode = d.description,
                 firstName = s.firstName,
                 middleName = s.middleName,
                 lastName = s.lastName,
                 street = s.street,
                 city = s.city,
                 state = s.state,
                 zip = s.zip,
                 position = s.position,
                 hearAbout = s.hearAbout,
                 referredby = s.referredBy,
                 email = s.email,
                 commentID = n.commentID,
                 commentDate = n.commentDate,
                 user = n.userID,
                 comment = n.comment
             }).ToList();

Answer 1

沿着这些方向尝试一些事情。分组提交的符号，然后仅commentDate检索第一次降序排序：

var result = from s in db.Submissions
             join n in db.notations on s.AppID equals n.AppID
             where s.received >= dts && s.received <= dte
             group n by s into g
             let recentNotation = g.OrderDescendingBy(item => item.commentDate).First()
             select new ApplicationTrackingSystem.customModels.Export {
                 AppID = g.Key.AppId,
                 /* rest of s fields */,
                 commentID = recentNotation.commentID,
                 commentDate = recentNotation.commentDate,
                 user = recentNotation.userID,
                 comment = recentNotation.comment
             };

当Ivan纠正我时，使用GroupJoin更好：

var result = from s in db.Submissions
             join n in db.notations on s.AppID equals n.AppID into g
             from n in g.OrderDescendingBy(item => item.commentDate).First()
             where s.received >= dts && s.received <= dte
             select new ApplicationTrackingSystem.customModels.Export {
                 AppID = g.Key.AppId,
                 /* rest of s fields */,
                 commentID = n.commentID,
                 commentDate = n.commentDate,
                 user = n.userID,
                 comment = n.comment
             };

Linq to Entities查询 -

1 个答案: