/// <summary>
///
/// </summary>
/// <param name="select"></param>
/// <returns></returns>
protected override Expression VisitSelect(SelectExpression select)
{
switch (_dataType)
{
case Nequeo.Data.DataType.ConnectionContext.ConnectionDataType.OracleDataType:
case Nequeo.Data.DataType.ConnectionContext.ConnectionDataType.SqlDataType:
select = (SelectExpression)base.VisitSelect(select);
if (select.Skip != null)
{
SelectExpression newSelect = select.SetSkip(null).SetTake(null);
bool canAddColumn = !select.IsDistinct && (select.GroupBy == null || select.GroupBy.Count == 0);
if (!canAddColumn)
{
newSelect = newSelect.AddRedundantSelect(new TableAlias());
}
newSelect = newSelect.AddColumn(new ColumnDeclaration("ROW_NUM", new RowNumberExpression(select.OrderBy)));
// add layer for WHERE clause that references new rownum column
newSelect = newSelect.AddRedundantSelect(new TableAlias());
newSelect = newSelect.RemoveColumn(newSelect.Columns[newSelect.Columns.Count - 1]);
var newAlias = ((SelectExpression)newSelect.From).Alias;
ColumnExpression rnCol = new ColumnExpression(typeof(int), newAlias, "ROW_NUM");
Expression where;
if (select.Take != null)
{
where = new BetweenExpression(rnCol, Expression.Add(select.Skip, Expression.Constant(1)), Expression.Add(select.Skip, select.Take));
}
else
{
where = Expression.GreaterThan(rnCol, select.Skip);
}
if (newSelect.Where != null)
{
where = Expression.And(newSelect.Where, where);
}
newSelect = newSelect.SetWhere(where);
select = newSelect;
}
return(select);
default:
select = (SelectExpression)base.VisitSelect(select);
if (select.Skip != null)
{
SelectExpression newSelect = select.SetSkip(select.Skip).SetTake(select.Take);
select = newSelect;
}
return(select);
}
}
protected override Expression VisitSelect(SelectExpression select)
{
select = (SelectExpression)base.VisitSelect(select);
if (select.Skip != null)
{
SelectExpression newSelect = select.SetSkip(null).SetTake(null);
bool canAddColumn = !select.IsDistinct && (select.GroupBy == null || select.GroupBy.Count == 0);
if (!canAddColumn)
{
newSelect = newSelect.AddRedundantSelect(new TableAlias());
}
newSelect = newSelect.AddColumn(new ColumnDeclaration(COLUMN_NAME, new RowNumberExpression(select.OrderBy)));
// add layer for WHERE clause that references new rownum column
newSelect = newSelect.AddRedundantSelect(new TableAlias());
newSelect = newSelect.RemoveColumn(newSelect.Columns.Single(c => c.Name == COLUMN_NAME));
var newAlias = ((SelectExpression)newSelect.From).Alias;
ColumnExpression rnCol = new ColumnExpression(typeof(int), newAlias, COLUMN_NAME, null);
Expression where;
if (select.Take != null)
{
where = new BetweenExpression(rnCol, Expression.Add(select.Skip, Expression.Constant(1)), Expression.Add(select.Skip, select.Take));
}
else
{
where = rnCol.GreaterThan(select.Skip);
}
if (newSelect.Where != null)
{
where = newSelect.Where.And(where);
}
newSelect = newSelect.SetWhere(where);
select = newSelect;
}
return(select);
}