您可以使用嵌套集将数据存储在表中。
http://en.wikipedia.org/wiki/Nested_set_model#Example
我担心如果您打算不断添加新项目，您的数百万个节点可能会让生活变得困难。也许可以通过使用有理数而不是整数作为左右值来减轻这种担忧。添加深度列以加快您要求后代的愿望。我编写了一些 SQL 来创建您要求的表和存储过程。我是在 SQL Server 中完成的，语法可能略有不同，但执行的是所有标准 SQL 语句。此外，我只是手动确定每个节点的上限和下限。显然，您必须编写代码才能将这些节点插入（和维护）到您的数据库中。
CREATE TABLE Tree(
Node nvarchar(10) NOT NULL,
Value int NOT NULL,
L int NOT NULL,
R int NOT NULL,
Depth int NOT NULL,
);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('A', 100, 1, 28, 0);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('B', 100, 2, 3, 1);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('C', 300, 4, 5, 1);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('D', 150, 6, 25, 1);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('E', 200, 26, 27, 1);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('F', 400, 7, 8, 2);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('G', 250, 9, 10, 2);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('H', 500, 11, 12, 2);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('I', 350, 13, 21, 2);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('J', 100, 21, 22, 2);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('K', 50, 23, 24, 2);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('L', 100, 14, 15, 3);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('M', 300, 16, 17, 3);
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES ('N', 200, 18, 19, 3);
CREATE PROCEDURE grandValue
@Node NVARCHAR(10)
AS
BEGIN
SET NOCOUNT ON;
DECLARE @lbound INT;
DECLARE @ubound INT;
SELECT @lbound = L, @ubound = R FROM Tree WHERE Node = @Node
SELECT SUM(Value) AS Total FROM TREE WHERE L >= @lbound AND R <= @ubound
RETURN
END;
EXECUTE grandValue 'C';
EXECUTE grandValue 'I';
EXECUTE grandValue 'A';
CREATE PROCEDURE children
@Node NVARCHAR(10)
AS
BEGIN
SET NOCOUNT ON;
DECLARE @lbound INT;
DECLARE @ubound INT;
DECLARE @depth INT;
SELECT @lbound = L, @ubound = R, @depth=Depth FROM Tree WHERE Node = @Node
SELECT Node FROM TREE WHERE L > @lbound AND R < @ubound AND Depth = (@depth + 1)
RETURN
END;
EXECUTE children 'C';
EXECUTE children 'I';
EXECUTE children 'A';
CREATE PROCEDURE family
@Node NVARCHAR(10)
AS
BEGIN
SET NOCOUNT ON;
DECLARE @lbound INT;
DECLARE @ubound INT;
SELECT @lbound = L, @ubound = R FROM Tree WHERE Node = @Node
SELECT Node FROM TREE WHERE L > @lbound AND R < @ubound
RETURN
END;
EXECUTE family 'C';
EXECUTE family 'I';
EXECUTE family 'A';
CREATE PROCEDURE parent
@Node NVARCHAR(10)
AS
BEGIN
SET NOCOUNT ON;
DECLARE @lbound INT;
DECLARE @ubound INT;
DECLARE @depth INT;
SELECT @lbound = L, @ubound = R, @depth = Depth FROM Tree WHERE Node = @Node
SELECT Node FROM TREE WHERE L < @lbound AND R > @ubound AND Depth = (@depth - 1)
RETURN
END;
EXECUTE parent 'C';
EXECUTE parent 'I';
EXECUTE parent 'A';
CREATE PROCEDURE ancestor
@Node NVARCHAR(10)
AS
BEGIN
SET NOCOUNT ON;
DECLARE @lbound INT;
DECLARE @ubound INT;
SELECT @lbound = L, @ubound = R FROM Tree WHERE Node = @Node
SELECT Node FROM TREE WHERE L < @lbound AND R > @ubound
RETURN
END;
EXECUTE ancestor 'C';
EXECUTE ancestor 'I';
EXECUTE ancestor 'A';
首先要在表中创建嵌套集，您可以运行一些代码来生成插入或从第一个节点开始，然后依次添加每个附加节点 - 尽管因为每次添加都可能修改表中的许多节点设置时，在构建此数据库时可能会出现大量的数据库抖动。
这是一个将节点添加为另一个节点的子节点的存储过程：
CREATE PROCEDURE insertNode
@ParentNode NVARCHAR(10), @NewNodeName NVARCHAR(10), @NewNodeValue INT
AS
BEGIN
SET NOCOUNT ON;
DECLARE @ubound INT;
DECLARE @depth INT;
SELECT @ubound = R, @depth = Depth FROM Tree WHERE Node = @ParentNode
UPDATE Tree SET L = L + 2 WHERE L >= @ubound
UPDATE Tree SET R = R + 2 WHERE R >= @ubound
INSERT INTO Tree (Node, Value, L, R, Depth) VALUES (@NewNodeName, @NewNodeValue, @ubound, @ubound + 1, @depth + 1);
RETURN
END;
我从http://www.evanpetersen.com/item/nested-sets.html 那里得到这个，他还展示了一个很好的图形行走算法来创建初始 L 和 R 值。您必须增强它以跟踪深度，但这很容易。