如何使用LINQ或HQL执行以下SQL查询

Question

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

SELECT a.id，s.classes，COUNT（p.id），MAX（p.date）截至去年，MIN（p.date）为第一
FROM帐户
LEFT JOIN校补ON s.account_id = a.id
LEFT JOIN用户U ON u.account_id = a.id
LEFT JOIN点p的p.user_id = u.id
WHERE支付= “S”
GROUP BY一个。编号

这些表是相关的我n以下面的方式：

我也有ActiveRecord类的所有表定义正确的关系（如果我做查询步骤它的工作，但它很慢，因为有很多行），我试过了这在投掷以下The method or operation is not implemented -Exception

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() }; 

：这不工作的以下

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

Answer 1

发现使用HQL解决方案 - 我还是开了LINQ的解决方案：

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

我觉得你的Linq查询会是这样的：

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() 
      }; 

虽然我我不确定NHibernate会如何处理group by和Count()的组合。如果不产生错误，您可能想要查看生成的SQL最终的结果。

如果不工作，你可能想选择的记录后面，和组/应用程序尽数相反，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);