/// <summary> Previews and changes if necessary the entire (outermost) expression. </summary>
/// <param name="e"></param>
/// <remarks>
/// <para>
/// Derived classes can override this method to manipulate the entire expression prior to SQL generation.
/// </para>
/// </remarks>
public virtual SelectExpression PreviewSelect(SelectExpression e)
{
//None of the servers support in one query COUNT and Limit (FETCH NEXT for MS SQL)
if (e.HasLimit() && e.HasOutAggregates())
Util.Throw("Invalid LINQ expression: Server does not support COUNT(*) and LIMIT (MS SQL: FETCH NEXT) in one query.");
return e;
}
public override SelectExpression PreviewSelect(SelectExpression e)
{
base.PreviewSelect(e);
// SQL CE doesn't support 'ORDER BY' for 'SELECT COUNT(*)'
if (e.HasOrderBy() && e.HasOutAggregates())
e.OrderBy.Clear();
return e;
}
