Question

如何使用Castle ActiveRecords和LINQ或HQL执行以下查询？

选择a.id，s.classes，COUNT（p.id），MAX（p.date）AS last，MIN（p.date）AS first
  来自帐户a   LEFT JOIN school s ON s.account_id = a.id
  LEFT JOIN用户u ON u.account_id = a.id
  LEFT JOIN点p ON p.user_id = u.id
  付款=＆＃34; S＆＃34;
  GROUP BY a.id

表格按以下方式相关： ER-Diagramm

我也为所有表定义正确关系的表都有ActiveRecord类（如果我按步骤进行查询，但是因为有很多行，所以它很慢）我试过以下没有做过的事情。工作：

var result = from account in AccountRecord.Queryable
             join s in SchoolRecord.Queryable on account equals s.Account into schools
             from school in schools.DefaultIfEmpty(null)
             join user in UserRecord.Queryable on account equals user.Account
             join p in PointsRecord.Queryable on user equals p.User into points
             where account.PaymentType == "S"
             select new { Account = account, School = school, Count = points.Count() };

引发了以下The method or operation is not implemented - 例外情况：

NHibernate.Linq.Visitors.QueryModelVisitor.VisitGroupJoinClause（GroupJoinClause groupJoinClause，QueryModel queryModel，Int32 index）

Answer 1

使用HQL找到解决方案 - 我仍然可以使用LINQ解决方案：

HqlBasedQuery query = new HqlBasedQuery(typeof(AccountRecord),
    "SELECT a, s, COUNT(p), MIN(p.DateUTC), MAX(p.DateUTC) " +
    "FROM AccountRecord a " +
    "LEFT JOIN a.Schools s " +
    "LEFT JOIN a.Users u " +
    "LEFT JOIN u.Points p " +
    "WHERE a.PaymentType=:payment GROUP BY a.Id");
query.SetParameter("payment", "S");
var result = from object[] row in (ArrayList)ActiveRecordMediator.ExecuteQuery(query)
                select new
                {
                    Account = row[0] as AccountRecord,
                    School = row[1] as SchoolRecord,
                    Count = row[2],
                    First = (new DateTime(1970, 1, 1, 0, 0, 0, 0)).AddSeconds(Convert.ToDouble(row[3])),
                    Last = (new DateTime(1970, 1, 1, 0, 0, 0, 0)).AddSeconds(Convert.ToDouble(row[4]))
                };

Answer 2

我认为您的Linq查询类似于：

var result = from a in AccountRecord.Queryable
             join s in SchoolRecord.Queryable on a.id equals s.account_id
             join u in UserRecord.Queryable   on a.id equals u.account_id
             join p in PointsRecord.Queryable on u.id equals p.user_id
             where a.payment == "S"
             group by a.id
             select new
             {
               Account = a,
               School = s,
               Count = p.Count()
             };

虽然我不确定NHibernate将如何处理group by和Count()组合。您可能希望查看生成的SQL最终是什么，如果它没有引发错误。

如果这不起作用，您可能希望重新选择记录，并在应用程序中对它们进行分组/计数，更像是：

var data = from a in AccountRecord.Queryable
           join s in SchoolRecord.Queryable on a.id equals s.account_id
           join u in UserRecord.Queryable   on a.id equals u.account_id
           join p in PointsRecord.Queryable on u.id equals p.user_id
           where a.payment == "S"
           select new
           {
             Account = a,
             School = s,
             Count = c
           };
var grouped = data.ToList.GroupBy(x => x.Account.Id);

如何使用LINQ或HQL执行以下SQL查询

2 个答案: