Shulou(Shulou.com)06/02 Report--

What this article shares with you is about how to understand the function of ADO.NET. The editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

First of all, I think ADO.NET is a very useful component, and if it continues to be improved and enhanced, I think the plugin will be used by more developers. The study of ADO.NET functions is very helpful for us to master how to create ADO.NET correctly, and we can also learn a lot of programming skills, such as delegate and template methods. I hope you can study it together.

We can receive it by passing in a variable of type DataReader when executing the Execute method. ADO.NET function is very simple to read only one record at a time, and can only be read-only, so it is very efficient and can reduce the network load. Since Command objects automatically generate DataReader objects, we only need to declare a variable referring to the DataReader object to receive it, and we do not need to use the New operator to generate it; another thing to note is that DataReader objects can only be used with the ADO.NET function, and the Connection object remains online during operation.

The following program code snippet returns a DataReader object that can read all records in the Members data table:

Dim cmA As ADOCommand= New ADOCommand ("Command string", "Provider=Microsoft.Jet.OLEDB.4.0;" & "Data Source=C:\ Inetpub\ wwwroot\ cr\ ch05\ MyWeb.mdb") Dim drA as ADODataReader cmA.ActiveConnection.Open () cmA.CommandText= "Select * From Members" cmA.Execute (drA)

The above program code snippet uses the Read method to retrieve the data, then uses the Item collection to extract the data of the UserId field in the way of key value (Key), and uses the index value (Index) to obtain the data of the user's UserPwd field. The index value is counted from 0, so the index value of * * fields is 0, and so on.

A detailed discussion on using access to ADO.NET

Connect ADO.NET SqlDataAdapter object data

Development and compatibility of ADO.NET DbProviderFactories

How to use ADO.Net program and matters needing attention

General description of ADO.NET model authentication

When the data is read, the Read method returns False, so it jumps out of the loop. GetValue method We can also use the GetValue method to get the record in the specified field, which is similar to the Item property, but the parameter of the GetValue method only receives the index value, not the key value as a parameter.

In ADO, all of these methods correspond to different types of cursors. In this article, you will find that although the function of ADO.NET is different from ADO, it has all the functions of ADO. In contrast, your code will extract data from the actual data source and its physical storage media and formats.

The above is how to understand the functions of ADO.NET, the editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.