假设我理解正确，它应该像从叶节点向后递归一样简单（这很容易，因为表Items仅存储叶节点）：
;with AncestryTree as ( select Item, Parent from Items where Parent is not null union all select Items.Item, t.Parent from AncestryTree t join Items on t.Item = Items.Parent )select * from AncestryTreeorder by Item, Parent
SQL Fiddle演示
