asp.net中datareader對(duì)象的簡(jiǎn)單使用
2024-07-10 12:56:57
供稿：網(wǎng)友
datareader對(duì)象作為一個(gè)asp.net中讀取記錄的一個(gè)比較好的控件,它的最大的優(yōu)點(diǎn)就是速度快,使用頻繁,而且在網(wǎng)站訪問(wèn)量很大的情況下,避免了因dataset對(duì)象過(guò)多的占用內(nèi)存空間,造成服務(wù)器負(fù)擔(dān)過(guò)重的情況.從而大大提高性能!
當(dāng)然,它也有不好的地方,那就是datareader對(duì)象只能是根據(jù)read()方法判斷,是一個(gè)只讀的,僅向前的數(shù)據(jù)流.此外可以通過(guò)command對(duì)象的executereader來(lái)創(chuàng)建該對(duì)象.
下面是關(guān)于該控件的基本使用代碼,希望對(duì)大家有用
<%@ page language="vb" contenttype="text/html" responseencoding="gb2312" %>
<%@ import namespace="system.data"%>
<%@ import namespace="system.data.sqlclient"%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en" "http://www.w3.org/tr/html4/loose.dtd">
<html>
<head>
<script language="vb" runat="server">
sub page_load(sender as object,e as eventargs)
dim cnn as sqlconnection
dim cmd as sqlcommand
dim html as string
dim datar as sqldatareader
'建立連接對(duì)象
cnn=new sqlconnection("server=lyws;uid=sa;pwd=sa;database=book")
cmd=new sqlcommand("select * from bookinfo",cnn)
cmd.connection.open()
'將結(jié)果集賦給datareader對(duì)象
datar=cmd.executereader()
response.write("<center><h2>圖書(shū)信息表<h2><center>")
response.write("<center><table border=1 style='width:18cm'>")
response.write("<tr>")
response.write("<th>圖書(shū)代碼</th>")
response.write("<th>圖書(shū)名稱</th>")
response.write("<th>出版社</th>")
response.write("<th>定價(jià)</th>")
response.write("<th>版別</th>")
response.write("<th>作者</th>")
response.write("</tr>")
try
'調(diào)用datareader對(duì)象的reader方法,通過(guò)while循環(huán),遍利結(jié)果集
while (datar.read())
response.write("<tr>")
response.write("<td align='center'>" + datar("圖書(shū)代碼").tostring() + "</td>")
response.write("<td>" + datar("圖書(shū)名稱").tostring() + "</td>")
response.write("<td>" + datar("出版社").tostring() + "</td>")
response.write("<td align='right'>" + datar("定價(jià)").tostring() + "</td>")
response.write("<td>" + datar("版別").tostring() + "</td>")
response.write("<td>" + datar("作者").tostring() + "</td>")
response.write("</tr>")
end while
response.write("</table></center>")
finally
datar.close()
cnn.close()
end try
end sub
</script>
<meta http-equiv="content-type" content="text/html; charset=gb2312">
<title>datareader對(duì)象測(cè)試!</title>
</head>
<body bgcolor="#9999ff">
<br>
<br>
<hr width="70%" align="center">
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</body>
</html>
