public override Linq.Translation.SqlGen.SqlStatement GetOrderByColumn(Linq.Translation.SqlGen.SqlStatement expression, bool descending)
 {
     string result = string.Format("{0} COLLATE NOCASE", expression);
       if(descending)
     result += " DESC";
       return result;
 }

		public virtual object Visit (Linq.QueryExpression queryExpression)
		{
			return null;
		}

 virtual public void VisitLinqExpression(Linq.LinqExpression x)
 {
     VisitQueryBody(x.Body);
 }

 virtual public void VisitWhereClause(Linq.WhereClause x)
 {
     VisitElement(x.Expression);
 }

 virtual public void VisitOrderByClause(Linq.OrderByClause x)
 {
     foreach (Linq.OrderingClause item in x.OrderingClauses)
         VisitElement(item);
 }

 virtual public void VisitOrderingClause(Linq.OrderingClause x)
 {
     VisitElement(x.Expression);
 }

 virtual public void VisitIntoClause(Linq.IntoClause x)
 {
     VisitElement(x.KeyVar);
     VisitElement(x.ValueVar);
     VisitQueryBody(x.NextQuery);
 }

 virtual public void VisitGroupByClause(Linq.GroupByClause x)
 {
     VisitElement(x.GroupExpr);
     VisitElement(x.ByExpr);
 }

 virtual public void VisitSelectClause(Linq.SelectClause x)
 {
     VisitElement(x.Expression);
 }

 virtual public void VisitFromClause(Linq.FromClause x)
 {
     foreach (Linq.Generator g in x.Generators)
         VisitElement(g);
 }

 virtual public void VisitGenerator(Linq.Generator x)
 {
     VisitElement(x.Expression);
 }

 virtual internal void VisitLinqTuple(Linq.LinqTuple x)
 {
     VisitElement(x.LastItem);
     foreach (Linq.OrderingClause item in x.OrderingItems)
         VisitElement(item);
 }

 virtual internal void VisitLinqTupleItemAccess(Linq.LinqTupleItemAccess x)
 {
     // nothing
 }

 virtual internal void VisitLinqOpChain(Linq.LinqOpChain x)
 {
     VisitElement(x.Expression);
 }

 virtual public void VisitQueryBody(Linq.QueryBody x)
 {
     foreach (Linq.FromWhereClause item in x.FromWhere)
         VisitElement(item);
 }