internal static bool HasAggregates(SelectExpression expression)
{
AggregateChecker checker = new AggregateChecker();
checker.Visit(expression);
return(checker._hasAggregate);
}
private static bool CanMergeWithFrom(SelectExpression select, bool isTopLevel)
{
SelectExpression fromSelect = GetLeftMostSelect(select.From);
if (fromSelect == null)
{
return(false);
}
//if (!IsColumnProjection(fromSelect)) return false;
bool selHasNameMapProjection = IsNameMapProjection(select);
bool selHasOrderBy = select.OrderBy != null && select.OrderBy.Count > 0;
bool selHasGroupBy = select.GroupBy != null && select.GroupBy.Count > 0;
bool selHasAggregates = AggregateChecker.HasAggregates(select);
bool selHasJoin = select.From is JoinExpression;
bool frmHasOrderBy = fromSelect.OrderBy != null && fromSelect.OrderBy.Count > 0;
bool frmHasGroupBy = fromSelect.GroupBy != null && fromSelect.GroupBy.Count > 0;
bool frmHasAggregates = AggregateChecker.HasAggregates(fromSelect);
// both cannot have orderby
if (selHasOrderBy && frmHasOrderBy)
{
return(false);
}
// both cannot have groupby
if (selHasGroupBy && frmHasGroupBy)
{
return(false);
}
// cannot move forward order-by if outer has group-by
if (frmHasOrderBy && (selHasGroupBy || selHasAggregates || select.IsDistinct))
{
return(false);
}
// cannot move forward a limit or an offset if outer has distinct
if (fromSelect.Limit != null && fromSelect.Offset != null && (select.IsDistinct || selHasAggregates || selHasGroupBy || selHasJoin))
{
return(false);
}
// cannot move forward a distinct if outer has groupby or a different projection
if (fromSelect.IsDistinct && (!selHasNameMapProjection || selHasGroupBy || selHasAggregates || (selHasOrderBy && !isTopLevel) || selHasJoin))
{
return(false);
}
if (frmHasAggregates && (select.IsDistinct || selHasAggregates || selHasGroupBy || selHasJoin))
{
return(false);
}
return(true);
}