Program | data | Database ASP is a new technology introduced by Microsoft to replace CGI, and is now recognized as the best tool for building Windows NT dynamic sites. With the full combination of ADO (Active data Object, a new data access model), it provides a powerful database access function, which makes it an important means for online database management.
First, ASP Introduction
The ASP includes five built-in ActiveX server components and five built-in objects: Database access component, file access component (Files accessing component), Ad rotator Component (Advertisement Carousel component), Content Linking component (contents link component), Browser capabilities component (Browser letter component), and request (requesting object), Servers (server objects), sessions (Session objects), Response (response objects), application (Application objects). Among all ASP components, the most useful is the database access component, also known as an ActiveX Data object or ADO. This component and the objects contained in it will be used in the site publishing database to complete reading and writing to the ODBC data source.
In addition, another important feature of ASP technology is that programmers can make use of Java, Visual Basic, Visual C + +, and other languages to adapt to their special needs of the ActiveX server components to expand the functionality of the ASP, so that their dynamic web pages have almost unlimited capacity to expand, This is not the traditional CGI program.
Development of database retrieval program based on WWW in combination with ADO
ASP technology combined with ADO technology, can realize the database management function based on WWW, the user can retrieve, input, update and delete the database information in the browser screen, thus establish the homepage content that provides the database information. ADO mainly provides seven objects and four sets to manage the database, including: Connection, Command, Parameter, Recordset, Field, property, error, and fields, Properties , Parameters, Errors. The connection object is used to establish a connection to the database, and the command object completes operations on the database, which can view or manipulate the data returned in the database. The Field object and the Fields collection allow you to manipulate each field in the current record, and the Parameter object and the Parameters collection provide information and data for the Command object. The objects and Properties collection provides information for the attributes of the connection, Command, Recordset, Field object, and the Error object and the Errors collection provide the wrong information when the error occurs.
The following is an introduction to the basic design methods for developing database retrieval programs:
⒈ Create the database source name (DSN). DSN is a database logical name that is created by ODBC and that is used and recognized by ODBC to connect applications and background databases. The specific method of creating an ODBC data source can be found in the relevant information, which is not covered here. Suppose you have created an ODBC data source named "book" for a SQL Server database.
⒉ Create a database link (Connection). The CreateObject method of the server object enables you to create connection objects and use variables to accept object references. Once the connection object is created, it can be used to open a connection to any ODBC data source. are as follows:
Dim conn ' Declare variable
Set conn=server.creatobject ("ADODB. Connection ")" Create a linked object
Conn.Open "book", Iusr_tsg01, "" "Open the link to ODBC, where IUSR_TSG01 is the authorized user ID number, the user password is not set. Programmers should be replaced according to their own circumstances.
⒊ creates a data object (Recordset). A Recordset is a more complex object in ADO, with many properties and methods, including: Eof (end of file), Bof (file header), AbsolutePage (Absolute page), Recordcount (Record Count), Common methods such as PageCount (page count) and MoveFirst (move to first record), MoveLast (move to last record), MoveNext (move to Next record), MovePrevious (move to previous record). The data object is combined with the ASP's session object, and can also realize the paging processing of the retrieval result.
Dim Rs ' declaration variable
Set rs=server.creatobject ("ADODB. Recordset ")" To create a data object
rs.pagesize=10 ' Sets the number of records displayed on a page
⒋ operations database. ADO implements the retrieval function by executing standard SQL statements, so you first define the SQL query statement and then execute the query command, which ultimately forms a collection of retrieved results.
Dim SQL ' declare variable
Sql= "SELECT * Publication where title like ' asp%% '" "Defines the SQL query statement that retrieves the records of all books in the publication table of the database that begin with ASP
Const adopenkeyset=1 ' defines the type of the recordset
Rs.Open Sql,conn, adOpenKeyset ' executes the SQL statement, saving the retrieved results in the data Object Rs.
⒌ returns results in ASP. If you are ready to display the book information in the check in the browser, you can use the following two ways:
<% Response.Write (Rs. ("Title"))%> or
⒍ closes database objects and linked objects. Be sure to close the ADO object before the program ends and release the server resources. As follows:
Here is an extremely simple search program that will help you understand some of the concepts.
<title>asp Database Retrieval Example </title>
Set Conn = Server.CreateObject ("ADODB. Connection ")
Sql= "SELECT * from publication where title like ' asp%% '"
Set rs=server.createobject ("Adodb.recordset")
Rs.Open Sql,conn, adOpenKeyset
<strong> Search word hit rate:<%=rs.recordcount%><br><br>
Do as not rs.eof
<option><% =rs ("title")%></option>
I use ASP technology to develop the Yantai University Library online Bibliographic Retrieval program, the practice proved that this method is simple, practical and efficient, is a very worthy of learning a method.