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This article will explain in detail about ADO.NET database commands and how to use them. The content of the article is of high quality, so the editor will share it with you for reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

The following describes the creation and maintenance of the ADO.NET database: establish a connection to the ADO.NET database, send select commands to the connection, use the DataReader object to save the returned results, and then get the data through the loop DataReader.

A command (Command) can be expressed in typical SQL statements, including performing a select query (select query) to return a recordset, an action query (action query) to update (add, edit, or delete) the records of the database, or to create and modify the table structure of the database. Of course, the command (Command) can also pass parameters and return a value.

Commands can be clearly defined, or stored procedures in the ADO.NET database can be called. The following snippet of code demonstrates how to issue a Select command after a connection is established.

[C #] String SQLStmt = "SELECT * FROM Customers"; ADOCommand myCommand = new ADOCommand (SQLStmt, myConn); [VB] Dim SQlStmt As String = "SELECT * FROM Customers" Dim myCommand As ADOCommand = New ADOCommand (SQLStmt, myConn)

When you are dealing with a large amount of ADO.NET data, a large amount of memory consumption can lead to performance problems. For example, if a connection (connection) reads 1000 rows of ADO.NET database records with a traditional ADO Recordset object, memory must be allocated to the connection for those 1000 rows until the end of the connection's life cycle. If 1000 users do the same thing on the same computer at the same time, overuse of memory will become a critical problem.

To solve these problems, the .NET Framework includes a DataReaders object that simply returns a read-only, forward data stream from the database. And there is only one record at a time in the current memory. The DataReader interface supports a variety of data sources, such as relational and hierarchical data. DataReader can be used when only a simple read-only recordset is returned after running a command.

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