Three Types of connection objects in ADO.NET.

1.OleDbConnection object : Use an OleDbConnection object to connect to a Microsoft Access or third-party database, such as MySQL. OLE database connections use the OleDbDataAdapter object to perform commands and return data.
2.SqlConnection object : Use a SqlConnection object to connect to a Microsoft SQL Server database. SQL database connections use the SqlDataAdapter object to perform commands and return data.
3.OracleConnection object : Use an OracleConnection object to connect to Oracle databases. Oracle database connections use the OracleDataAdapter object to perform commands and return data. This connection object was introduced in Microsoft .NET
Framework version 1.1.