What is the Connection Object ?

Whether you are working in connected or disconnected mode the first thing you have to do is to create a connection.
You can create a connection to a database by creating a Connection object.
This object is responsible for establishing a connection to the data source.

Dim objDataConnection As System.Data.SqlClient.SqlConnection 
Dim objDataConnection As System.Data.OleDb.OleDbConnection 

SqlConnection

The connection string usually contains the following:

objDataConnection.ConnectionString =  "Data Source=(local);User ID=sa;Initial Catalog=pubs" 

objDataConnection.ConnectionString =  "Server=betsol01;Database=prod;Trusted_Connection=True;" 

OleDbConnection

The connection string usually contains the following:
Provider - Specifies the name of the provider you are using to connect to the database.
Data Source - Specified where the database is. It can be a folder path or the name of the machine where the database is located.
User ID and Password - Specifies a valid user name and password.
Initial Catalog - Specifies the name of the database when you are connecting to a SQL Server or Oracle database.

objDataConnection.ConnectionString =  "Provider=Microsoft.Jet.OLEDB.4.0;" & _ 
                                     "Password=;User ID=Admin;" & _ 
                                     "Data Source:=C:\Temp\Testing.mdb" 

objDataConnection.ConnectionString =  "Server=localhost;Uid=sa;Pwd=;Database=norwind" 
objDataConnection.ConnectionString =  "Server=localhost;Uid=sa;Pwd=;Database=norwind;Connection Timeout=30" 

Creating a Connection Object

Dim objDataConnection As System.Data.OleDb.OleDbConnection 
objDataConnection = New System.Data.OleDb.OleDbConnection 
objDataConnection.ConnectionString = "connectionstring" 
objDataConnection.Open 

Alternatively you could pass the connection string directly to the constructor.

Dim objDataConnection = New System.Data.OleDb.OleDbConnection("connectionstring") 
objDataConnection.Open 

Closing a Connection

objDataConnection.Close 

Properties

Methods

Events

Changing the Timeout

The ConnectionTimeout property is readonly but can be changed by including a different value in the connection string.

objConnection.ConnectionString = "Provider=SQLOLEDB; 
                                 Persist Security Info=False; 
                                 User Id = sa; 
                                 Initial Catalog = dbName; 
                                 Data Source = localhost; 
                                 Connect Timeout = 20;