问将标准Mysql表转换为嵌套表

EN

     CREATE TABLE Tree (
    child CHAR(10) NOT NULL, 
    parent CHAR(10), 
    CONSTRAINT PK_Tree PRIMARY KEY CLUSTERED(child))

     -- insert the sample data for testing 

     INSERT INTO Tree(child,parent) VALUES ('Albert', NULL)
     INSERT INTO Tree(child,parent) VALUES ('Bert', 'Albert') 
     INSERT INTO Tree(child,parent) VALUES ('Chuck', 'Albert') 
     INSERT INTO Tree(child,parent) VALUES ('Donna', 'Chuck') 
     INSERT INTO Tree(child,parent) VALUES ('Eddie', 'Chuck') 
     INSERT INTO Tree(child,parent) VALUES ('Fred', 'Chuck') 


CREATE TABLE Stack (
    StackID int IDENTITY(1,1),
    stack_top INTEGER NOT NULL, 
    child VARCHAR(10) NOT NULL, 
    lft INTEGER NOT NULL, 
    rgt INTEGER, 
    CONSTRAINT PK_Stack PRIMARY KEY CLUSTERED(StackID))


    DECLARE @lft_rgt INTEGER, @stack_pointer INTEGER, @max_lft_rgt INTEGER

    SET @max_lft_rgt = 2 * (SELECT COUNT(*) FROM Tree)

    INSERT INTO Stack 
    SELECT 1, child, 1, @max_lft_rgt 
    FROM Tree 
    WHERE parent IS NULL

    SET @lft_rgt = 2

    SET @Stack_pointer = 1

    DELETE FROM Tree WHERE parent IS NULL

    -- The Stack is now loaded and ready to use 

    WHILE (@lft_rgt < @max_lft_rgt) 
        BEGIN 
            IF EXISTS (SELECT * FROM Stack AS S1, Tree AS T1 WHERE S1.child = T1.parent AND S1.stack_top = @stack_pointer) 
                BEGIN 
                    -- push when stack_top has subordinates and set lft value 
                    INSERT INTO Stack 
                    SELECT (@stack_pointer + 1), 
                    MIN(T1.child), 
                    @lft_rgt, 
                    NULL 
                    FROM Stack AS S1, 
                    Tree AS T1 
                    WHERE S1.child = T1.parent AND S1.stack_top = @stack_pointer

                     -- remove this row from Tree 
                     DELETE FROM Tree 
                     WHERE child = (SELECT child FROM Stack WHERE stack_top = @stack_pointer + 1)

                     SET @stack_pointer = @stack_pointer + 1 
                END 
        -- push 
        ELSE 
            BEGIN 
                -- pop the Stack and set rgt value 
                UPDATE Stack SET rgt = @lft_rgt, stack_top = -stack_top 
                WHERE stack_top = @stack_pointer 

                SET @stack_pointer = @stack_pointer - 1
            END

            -- pop 
        SET @lft_rgt = @lft_rgt + 1
    END