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bbs树形结构的实现方法（一） |
bbs的树形结构显示可以有很多种方法，其中比较容易想到的是递归和排序串方法，但这两种方法并不是很好，那么怎样才算是比较合理的算法呢？
递归方法不用讲，大家都知道怎么用，先讲讲排序串方法，最简单的排序串方法可以这样用,只用一个id就可以完成树型，向这样
1 001
2 002
3 001001
4 001001001
5 001002001
用这个字符串排序后就变成这样：
001
001001
001001001
001002001
002
这种方法容易实现，但缺点也是很明显，一个是回帖数受限制，另一个随着回帖增加会越来越长，影响数据库效率。
下面一种方法是李龙的，属于变通的排序串方法
DDL
--------------
CREATE TABLE dbo.Message
(
ID numeric(18,0) IDENTITY(1000,1),
DateAndTime datetime DEFAULT getdate() NOT NULL,
AuthorID numeric(18,0) NOT NULL,
Subject nvarchar(250) NOT NULL,
Body ntext NULL,
LinkURL nvarchar(100) NULL,
TextForLink nvarchar(50) NULL,
ImageURL nvarchar(100) NULL,
Class int DEFAULT 0 NOT NULL,
ClientInfo nvarchar(250) NULL,
RemoteAddr nvarchar(50) NULL,
CONSTRAINT PK_BBSMessage
PRIMARY KEY NONCLUSTERED (ID,AuthorID)
)
go
CREATE TABLE dbo.MsgRefTab
(
MsgID numeric(18,0) NOT NULL,
ParentID numeric(18,0) NOT NULL,
AncestorID numeric(18,0) NOT NULL,
ChildNum numeric(18,0) DEFAULT 0 NOT NULL,
LinkStr nvarchar(250) NOT NULL,
CONSTRAINT PK_BBSRefTab
PRIMARY KEY NONCLUSTERED (MsgID)
)
go
-----------------
存储过程:
-----------------
-- 抽出
CREATE PROCEDURE sp_Summary
@HaveBody bit,
@from numeric,
@to numeric
AS
IF (@HaveBody = 1)
select t.ID,t.DateAndTime,m.Nickname as
Author,m.Email,t.Subject,t.Body,t.LinkURL,t.TextForLink,t.ImageURL,s.ChildNu
m,s.ParentID
from Message t
,MsgRefTab AS s
,(SELECT MsgID FROM MsgRefTab WHERE ParentID = 0) AS f
,Members AS m
where t.ID=s.MsgID
and f.MsgID = s.AncestorID
and f.MsgID between @from and @to
and m.MemberID = t.AuthorID
order by s.AncestorID,s.LinkStr
ELSE
select t.ID,t.DateAndTime,m.Nickname as
Author,m.Email,t.Subject,t.LinkURL,t.TextForLink,t.ImageURL,s.ChildNum,s.Par
entID
from Message t
,MsgRefTab AS s
,(SELECT MsgID FROM MsgRefTab WHERE ParentID = 0) AS f
,Members AS m
where t.ID=s.MsgID
and f.MsgID = s.AncestorID
and f.MsgID between @from and @to
and m.MemberID = t.AuthorID
order by s.AncestorID,s.LinkStr
go
-- 加贴
CREATE PROCEDURE sp_Add_Message
@AuthorID numeric,
@Subject nvarchar(250),
@Body ntext,
@LinkURL nvarchar(100),
@TextForLink nvarchar(50),
@ImageURL nvarchar(100),
@ParentID numeric,
@ID nu |
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