ASP.NET - Rarruwar yauyau

ADO.NET naɗa ɗanɗin ɗanɗin .NET.

Yanar ADO.NET ce yin aiki da rarruwar yauyau. Ta ADO.NET, ka iya aiki da yauyau ne.

Yanar

Rarruwar yauyau - kama a Repeater
Rarruwar yauyau - kama a DataList

Koye ADO.NET shi?

  • ADO.NET naɗa ɗanɗin ɗanɗin .NET
  • ADO.NET consists of a series of classes used to operate data access
  • ADO.NET is completely based on XML
  • ADO.NET does not have a Recordset object, unlike ADO

create database connection

We intend to use the Northwind database that we have used before.

First, import the namespace "System.Data.OleDb". We need this namespace to be able to operate Microsoft Access and other OLE DB data providers. We will create a connection to this database in the Page_Load subroutine. We created a dbconn variable and assigned a new OleDbConnection class to it, which has a connection string that can indicate OLE DB and the location of the database. Then we opened this database connection:

<%@ Import Namespace="System.Data.OleDb" %>
<script runat="server">
sub Page_Load
dim dbconn
dbconn=New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;
data source=" & server.mappath("northwind.mdb"))
dbconn.Open()
end sub

Note:This connection string must be a continuous string without line breaks!

create database command

To specify the records to be retrieved from the database, we will create a dbcomm variable and assign a new OleDbCommand to it. This OleDbCommand class is used to issue SQL queries against database tables:

<%@ Import Namespace="System.Data.OleDb" %>
<script runat="server">
sub Page_Load
dim dbconn,sql,dbcomm
dbconn=New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;
data source=" & server.mappath("northwind.mdb"))
dbconn.Open()
sql="SELECT * FROM customers"
dbcomm=New OleDbCommand(sql,dbconn)
end sub

create DataReader

The OleDbDataReader class is used to read a record stream from the data source. By calling the ExecuteReader method of the OleDbCommand object, you can create a DataReader:

<%@ Import Namespace="System.Data.OleDb" %>
<script runat="server">
sub Page_Load
dim dbconn,sql,dbcomm,dbread
dbconn=New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;
data source=" & server.mappath("northwind.mdb"))
dbconn.Open()
sql="SELECT * FROM customers"
dbcomm=New OleDbCommand(sql,dbconn)
dbread=dbcomm.ExecuteReader()
end sub

bind to Repeater control

then, we bind this DataReader to a Repeater control:

<%@ Import Namespace="System.Data.OleDb" %>
<script runat="server">
sub Page_Load
dim dbconn,sql,dbcomm,dbread
dbconn=New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;
data source=" & server.mappath("northwind.mdb"))
dbconn.Open()
sql="SELECT * FROM customers"
dbcomm=New OleDbCommand(sql,dbconn)
dbread=dbcomm.ExecuteReader()
customers.DataSource=dbread
customers.DataBind()
dbread.Close()
dbconn.Close()
end sub













Companyname
Contactname
Address
City





<%#Container.DataItem("companyname")%>
<%#Container.DataItem("contactname")%>
<%#Container.DataItem("address")%>
<%#Container.DataItem("city")%>

显示这个例子

关闭数据库连接

在不在需要访问数据库后，请记得始终将 DataReader 和数据库连接关闭：

dbread.Close()
dbconn.Close()