Question

How can I execute the following query using Castle ActiveRecords and LINQ or HQL?

SELECT a.id, s.classes, COUNT(p.id), MAX(p.date) AS last, MIN(p.date) AS first
FROM account a
LEFT JOIN school s ON s.account_id = a.id
LEFT JOIN user u ON u.account_id = a.id
LEFT JOIN points p ON p.user_id = u.id
WHERE payment = “S”
GROUP BY a.id

The tables are related in the following way:

I also have ActiveRecord classes for all tables with the correct relations defined (if I do the query in steps it works, but it is slow as there are a lot of rows) and I tried the following which didn’t worked:

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() };

which threw the following The method or operation is not implemented-Exception at:

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

Answer 1

Found the solution using HQL – I’m still open for a LINQ solution:

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]))
                };