Visual Basic .NET - ADO .Net - Introduction

ADO.NET (ActiveX Data Objects for .NET) is a data access technology provided by Microsoft as part of the .NET Framework. It is used for accessing and manipulating data from different data sources, such as databases, XML files, and web services. ADO.NET provides a set of classes and components that facilitate database connectivity, data retrieval, data manipulation, and data presentation in VB.NET applications.

Key components of ADO.NET:

Connection: ADO.NET provides various classes for establishing a connection to a data source, such as SqlConnection for SQL Server, OleDbConnection for OLE DB data sources, and OdbcConnection for ODBC data sources. The Connection object represents the connection to the database and provides methods for opening, closing, and managing the connection.

Command: ADO.NET uses Command objects (SqlCommand, OleDbCommand, OdbcCommand) to execute queries or commands against the data source. Commands can be used to retrieve data using SELECT statements, modify data using INSERT, UPDATE, DELETE statements, or execute stored procedures.

DataReader: The DataReader object (SqlDataReader, OleDbDataReader, OdbcDataReader) is used for retrieving data in a forward-only, read-only manner from a data source. It provides a fast and efficient way to fetch large sets of data.

DataSet: ADO.NET introduces the DataSet class, which is an in-memory representation of data retrieved from a data source. The DataSet can contain multiple DataTables, which represent the data structure and can be related to each other using DataRelations. The DataSet provides methods for querying and manipulating data, and it can be disconnected from the data source.

DataAdapter: The DataAdapter class acts as a bridge between the DataSet and the data source. It populates the DataSet with data retrieved from the database and also updates changes made in the DataSet back to the database. The DataAdapter uses Command objects to execute queries and commands against the database.

ADO.NET follows a disconnected data model, where the data is retrieved from the database, manipulated in memory using DataSets and DataTables, and then changes are pushed back to the database when required.

ADO.NET provides a flexible and efficient way to work with data in VB.NET applications, supporting various data sources and offering powerful features for data access and manipulation. It enables developers to build robust and scalable data-driven applications.