javascript asp教程Recordset记录

网络编程 2024/12/24 佚名

3 1 2

Recordset is another created/instanciated Object. It is a collection of data taken from a database. Recordset has 26 properties, 25 methods, 11 events, and two (2) collections. The vast majority of Recordset is beyond the scope of this web site.

Quick Aside:

The database we are using for lesson 16 and lesson 17 is an MS Access 2000 file (not the best database for large sites). The file is called htmlColor.mdb and it has a single Table called colorChart. The database Table has three columns and they are called ID, colorName, and hexValue.

The illustration below shows how we will cycle through these records.

ID colorName hexValue 1 Aqua 00FFFF 2 Beige F5F5DC 3 Crimson DC143C 4 Darkviolet 9400D3 5 ForestGreen 228B22 ID colorName hexValue 1 Aqua 00FFFF 2 Beige F5F5DC 3 Crimson DC143C 4 Darkviolet 9400D3 5 ForestGreen 228B22 ID colorName hexValue 1 Aqua 00FFFF 2 Beige F5F5DC 3 Crimson DC143C 4 Darkviolet 9400D3 5 ForestGreen 228B22

In this example we cycle through the records row by row. We will use the MoveNext() Method to go from record #1 to #2, etc. Then, we will access specific data in each row by using the column name.

Get Started:

Below is the script for Lesson 17. It's exactly the same as the script for lesson 16. The difference is that we will focus on those lines of code that deal with Recordsets.

<%@LANGUAGE="JavaScript"%>
<!-- METADATA TYPE="typelib" 
FILE="C:\Program Files\Common Files\System\ado\msado15.dll" -->
<HTML>
<BODY>
<%
var myConnect = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source="; 
myConnect += Server.MapPath("\\");
myConnect += "\\GlobalScripts\\htmlColor.mdb;";

var ConnectObj = Server.CreateObject("ADODB.Connection");
var RS = Server.CreateObject("ADODB.Recordset");
var sql="SELECT ID, colorName, hexValue FROM colorChart;";

ConnectObj.Open (myConnect);
RS.Open(sql,ConnectObj,adOpenForwardOnly,adLockReadOnly,adCmdText);

Response.Write("<TABLE BORDER=\"1\" CELLSPACING=\"0\">\r");
Response.Write("<TR><TH>ID</TH><TH>colorName</TH>");
Response.Write("<TH>hexValue</TH></TR>\r");
while (!RS.EOF)
	{
	Response.Write("<TR><TD>" +RS("ID")+ "</TD><TD BGCOLOR=\"#");
	Response.Write( RS("hexValue")+ "\">" + RS("colorName") );
	Response.Write("</TD><TD>" +RS("hexValue")+ "</TD></TR>\r");
	RS.MoveNext();
	}
Response.Write("</TABLE>\r");

RS.Close();
ConnectObj.Close();
RS = null;
ConnectObj = null;
%>
</BODY>
</HTML>

Click Here to run the script in a new window.

The DLL:

We'll dissect the Recordset statements from top to bottom. In this case that means starting with the Dynamic Link Library.

<!-- METADATA TYPE="typelib" 
FILE="C:\Program Files\Common Files\System\ado\msado15.dll" -->

What in the world is a DLL? A Dynamic Link Library holds values without tying up memory. Here's how it works. If you try to use a variable that is undefined, ASP will first look it up in the DLL. You'll notice in the Recorset.Open() Method that we use variables that are not defined in the script. Thanks to the DLL, we won't get an error code.

Managing the Recordset:

First we must instanciate a Recordset, which we do in the little snippet below.

var RS = Server.CreateObject("ADODB.Recordset");

Next we create a Text Command. The text in question comes in the form of S.Q.L. (Structured Query Language). SQL is beyond the scope of this web site, but the command below means select ID, colorName and hexValue from the colorChart Table.

var sql="SELECT ID, colorName, hexValue FROM colorChart;";

Then we open the Recordset. The five arguments in order are: source, connection, cursor type, lock type, and options .

RS.Open(sql,ConnectObj,adOpenForwardOnly,adLockReadOnly,adCmdText);

Using a loop, we tell ASP to do certain things for as long as we haven't hit EOF, which means End of File.

while (!RS.EOF)

Next, we access specific collums in the Recordset by name.

Response.Write( RS("hexValue") + "\">" + RS("colorName") );

Then we move down from one row of records to the next.

RS.MoveNext();

Finally, when we reach EOF, the loop relinquishes control and we can close the Recordset Object.

RS.Close();

The Rest of The Story:

This is by no means a complete lesson on Recordsets; it wasn't meant to be. The rest of the story on Recordsets is out there, on the internet, and in books. There is one other thing we have to talk about with Recordsets. We do that in lesson 18.

javascript,asp教程Recordset记录

华山资源网 Design By www.eoogi.com

广告合作：本站广告合作请联系QQ：858582 申请时备注：广告合作（否则不回）
免责声明：本站资源来自互联网收集,仅供用于学习和交流,请遵循相关法律法规,本站一切资源不代表本站立场,如有侵权、后门、不妥请联系本站删除！

华山资源网 Design By www.eoogi.com

评论“javascript asp教程Recordset记录”

暂无评论...

www.eoogi.com 华山资源网

120,135影音资源

344,641技术资源

22,817软件资源

435,032站长资源

javascript asp教程Recordset记录

javascript asp教程More About Recordsets

javascript asp教程创建数据库连接

评论“javascript asp教程Recordset记录”

稳了！魔兽国服回归的3条重磅消息！官宣时间再确认！

更新日志

友情链接