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实例荼晏狻⒆髡吆头⒈硎奔渌阉骷锹?lt;/B>
1、在例一的基础增加一个列表菜单,名称为tima,设置如下:

上图中的“不选定条件”值为空,稍后在记录集中设置它的默认值。其它的你自己可以任意添加选项和时间,一天前值为1,一年前值为365,依此类推。
2、打开高级记录集,设置如下:

上图那个MM_tima变量的默认值99999999是刚才“不选条件”值为空时,返回99999999,即查询99999999天前的记录,这个数值你可以自已设置,如果不选定时间,就查询你的数据中第一条记录插入时的时间,这样就搜索数据库的全部记录了。
这里比上例多了一个时间筛选条件bbs_tima>=now()-MM_tima,nwo()是获取当前系统日期时间的一个函数,用它减去选定多少天前的变量值,即可筛出发表时间大于或等于多少天前的记录。
以上两例都是单层SQL查询,你可以依照以上介绍的方法添AND条件,如果要同时查询两个字段,除了用AND外,还可用OR运算符,比如 WHERE bbs_title LIKE '%MM_title%' or bbs_uesr LIKE '%MM_uesr%' ,它查询bbs_title或者bbs_uesr字段符合搜索条件的记录。但有些记录,比如论坛回复贴子,因为它没有标题,bbs_title字段是空的,而我要根据回复内容搜索贴子时,就不能显示出主题标题。如何解决这个问题呢?用嵌套查询可实现这个目的。
实例三、按标题、作者、回复内容及发表时间搜索记录。
1把例二中的select列表菜单添多一项“回复内容”,如下图所示:

2、修改代码
切换到“代码”视图,找到这句代码:
Recordset1.Source = "SELECT * FROM bbs WHERE " + Replace(Recordset1__MM_sch, "'", "''") + " LIKE '%" + Replace(Recordset1__MM_text, "'", "''") + "%'and bbs_tima>=now()-" + Replace(Recordset1__MM_tima, "'", "''") + " and bbs_dist=0 ORDER BY bbsID DESC" 这是记录集SQL查询语句,把它改为:
Recordset1.Source = sql
然在在记录集代码段的第一行输入:
dim sql if Recordset1__MM_sch="bbs_book" then sql=" SELECT * FROM bbs WHERE bbsID IN (SELECT bbs_dist FROM bbs WHERE " + Replace(Recordset1__MM_sch, "'", "''") + " LIKE '%" + Replace(Recordset1__MM_text, "'", "''") + "%'and bbs_tima>=now()-" + Replace(Recordset1__MM_tima, "'", "''") + " and bbs_dist<>0 ORDER BY bbsID DESC) ORDER BY bbsID DESC" else sql="SELECT * FROM bbs WHERE " + Replace(Recordset1__MM_sch, "'", "''") + " LIKE '%" + Replace(Recordset1__MM_text, "'", "''") + "%'and bbs_tima>=now()-" + Replace(Recordset1__MM_tima, "'", "''") + " and bbs_dist=0 ORDER BY bbsID DESC" end if
放入位置下图(选中部分):

以上代码的简要说明:
由于要用到嵌套查询,所以使用判断语句根据用户选定的条件切换SQL语句,比如,当用户选择“回复内容”时,菜单列表返回值为“bbs_book”,执行下面这一段SQL语句:
sql=" SELECT * FROM bbs WHERE bbsID IN (SELECT bbs_dist FROM bbs WHERE " + Replace(Recordset1__MM_sch, "'", "''") + " LIKE '%" + Replace(Recordset1__MM_text, "'", "''") + "%'and bbs_tima>=now()-" + Replace(Recordset1__MM_tima, "'", "''") + " and bbs_dist<>0 ORDER BY bbsID DESC) ORDER BY bbsID DESC"
这是嵌套查询的语句,小括号()内的是子级查询,把符合搜索条件的记录筛出,然后把bbs_dist(注:这个字段记录主题ID号,对应所回复的主题的ID号)字段的值以列表形式返回主查询继续下一次查询,比如,程序执行时,()内的SQL语句优先执行,筛出符合条件的记录后,把它的bbs_dist的值返回主查询查询,如下:
SELECT * FROM bbs WHERE bbsID IN (12,35,41,45,87...)
这样,主查询语句就能把bbsid(ID号)等于12、35、41、45、87的记录全部筛出,而这些记录都是有标题的贴子。bbs_dist<>0表示只查询所有回复内容,不查询主题内容。
须要注意的是,子查询SELECT子句只能返回一个字段的值,如SELECT bbs_dist,否则将报错,若写成这样:
SELECT bbs_dist,bbs_id
报错如下:

如果不是选中“回复内容”,将由else切换为:
sql="SELECT * FROM bbs WHERE " + Replace(Recordset1__MM_sch, "'", "''") + " LIKE '%" + Replace(Recordset1__MM_text, "'", "''") + "%'and bbs_tima>=now()-" + Replace(Recordset1__MM_tima, "'", "''") + " and bbs_dist=0 ORDER BY bbsID DESC"
以上这段代码是单层查询,和第二例SQL语句是一样的。
好了,关于用DW MX做站内搜索就讲到这里,只要核心原理都告诉给你了,留一些思考的空间给你吧,自己去试验扩展它的功能。俺没时间了,就此告别。886!
下面是搜索结果页源代码(搜索页和结果页合拼在一起,实际上应把它分离开来):
<%@LANGUAGE="VBSCRIPT" CODEPAGE="936"%> <!--#include file="Connections/new.asp" --> <% Dim Recordset1__MM_text Recordset1__MM_text = "1" If (request.QueryString("text") <> "") Then Recordset1__MM_text = request.QueryString("text") End If %> <% Dim Recordset1__MM_sch Recordset1__MM_sch = "1" If (request.QueryString("select") <> "") Then Recordset1__MM_sch = request.QueryString("select") End If %> <% Dim Recordset1__MM_tima Recordset1__MM_tima = "99999999" If (request.QueryString("tima") <> "") Then Recordset1__MM_tima = request.QueryString("tima") End If %> <% dim sql if Recordset1__MM_sch="bbs_book" then sql=" SELECT * FROM bbs WHERE bbsID IN (SELECT bbs_dist,bbs_id FROM bbs WHERE " + Replace(Recordset1__MM_sch, "'", "''") + " LIKE '%" + Replace(Recordset1__MM_text, "'", "''") + "%'and bbs_tima>=now()-" + Replace(Recordset1__MM_tima, "'", "''") + " and bbs_dist<>0 ORDER BY bbsID DESC) ORDER BY bbsID DESC" else sql="SELECT * FROM bbs WHERE " + Replace(Recordset1__MM_sch, "'", "''") + " LIKE '%" + Replace(Recordset1__MM_text, "'", "''") + "%'and bbs_tima>=now()-" + Replace(Recordset1__MM_tima, "'", "''") + " and bbs_dist=0 ORDER BY bbsID DESC" end if Dim Recordset1 Dim Recordset1_numRows
Set Recordset1 = Server.CreateObject("ADODB.Recordset") Recordset1.ActiveConnection = MM_new_STRING Recordset1.Source = sql Recordset1.CursorType = 0 Recordset1.CursorLocation = 2 Recordset1.LockType = 1 Recordset1.Open()
Recordset1_numRows = 0 %> <% Dim Repeat1__numRows Dim Repeat1__index
Repeat1__numRows = 20 Repeat1__index = 0 Recordset1_numRows = Recordset1_numRows + Repeat1__numRows %> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <title>用DW MX打造站内搜索</title> </head>
<body> <form name="form1" method="get" action=""> <p>关键词: <input name="text" type="text" id="text" value="<%=request.QueryString("text")%>"> 选择条件: <select name="select"> <option value="bbs_uesr+bbs_title" <%If (Not isNull(request.QueryString("select"))) Then If ("bbs_uesr+bbs_title" = CStr(request.QueryString("select"))) Then Response.Write("SELECTED") : Response.Write("")%>>不选定条件</option> <option value="bbs_uesr" <%If (Not isNull(request.QueryString("select"))) Then If ("bbs_uesr" = CStr(request.QueryString("select"))) Then Response.Write("SELECTED") : Response.Write("")%>>作者</option> <option value="bbs_title" <%If (Not isNull(request.QueryString("select"))) Then If ("bbs_title" = CStr(request.QueryString("select"))) Then Response.Write("SELECTED") : Response.Write("")%>>标题</option> <option value="bbs_book" <%If (Not isNull(request.QueryString("select"))) Then If ("bbs_book" = CStr(request.QueryString("select"))) Then Response.Write("SELECTED") : Response.Write("")%>>回复内容</option> </select> <br> 选择时间: <select name="tima" id="tima"> <option value="" <%If (Not isNull(request.QueryString("tima"))) Then If ("" = CStr(request.QueryString("tima"))) Then Response.Write("SELECTED") : Response.Write("")%>>不选定条件</option> <option value="7" <%If (Not isNull(request.QueryString("tima"))) Then If ("7" = CStr(request.QueryString("tima"))) Then Response.Write("SELECTED") : Response.Write("")%>>一周前</option> <option value="31" <%If (Not isNull(request.QueryString("tima"))) Then If ("31" = CStr(request.QueryString("tima"))) Then Response.Write("SELECTED") : Response.Write("")%>>一个月前</option> <option value="182" <%If (Not isNull(request.QueryString("tima"))) Then If ("182" = CStr(request.QueryString("tima"))) Then Response.Write("SELECTED") : Response.Write("")%>>半年前</option> <option value="365" <%If (Not isNull(request.QueryString("tima"))) Then If ("365" = CStr(request.QueryString("tima"))) Then Response.Write("SELECTED") : Response.Write("")%>>一年前</option> </select> <input type="submit" name="Submit" value="搜索"> <br> </form> <table width="666" border="0" cellpadding="0" cellspacing="1" bgcolor="#FFCC33"> <tr bgcolor="#FFCC66"> <td width="291">标题</td> <td width="156">作者</td> <td width="219">发表时间</td> </tr> <% While ((Repeat1__numRows <> 0) AND (NOT Recordset1.EOF)) %> <tr bgcolor="#FFFFFF"> <td><%=replace((Recordset1.Fields.Item("bbs_title").Value),request.QueryString("text"), "<font color='#FF0000'>"&request.QueryString("text")&"</font>")%></td> <td><%=(Recordset1.Fields.Item("bbs_uesr").Value)%></td> <td><%=(Recordset1.Fields.Item("bbs_tima").Value)%></td> </tr> <% Repeat1__index=Repeat1__index+1 Repeat1__numRows=Repeat1__numRows-1 Recordset1.MoveNext() Wend %> </table> </body> </html> <% Recordset1.Close() Set Recordset1 = Nothing %>
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