error en la conexión con la base

[Avelar]

Aquí tienes unos ejemplos de la ayuda de SQL Server con respecto a una conexión de ADO.

Código:

Examples
A. Using SQLOLEDB to connect to an instance of SQL Server: setting individual properties
The following Microsoft Visual Basic® code fragments from the ADO Introductory Visual Basic Sample show how to use SQLOLEDB to connect to an instance of SQL Server. 

' Initialize variables.
Dim cn As New ADODB.Connection
. . .
Dim ServerName As String, DatabaseName As String, _
   UserName As String, Password As String

' Put text box values into connection variables.
ServerName = txtServerName.Text
DatabaseName = txtDatabaseName.Text
UserName = txtUserName.Text
Password = txtPassword.Text

' Specify the OLE DB provider.
cn.Provider = "sqloledb"

' Set SQLOLEDB connection properties.
cn.Properties("Data Source").Value = ServerName
cn.Properties("Initial Catalog").Value = DatabaseName

' Decision code for login authorization type: 
' Windows NT or SQL Server authentication.
If optWinNTAuth.Value = True Then
    cn.Properties("Integrated Security").Value = "SSPI"
Else
    cn.Properties("User ID").Value = UserName
    cn.Properties("Password").Value = Password
End If

' Open the database.
cn.Open

B. Using SQLOLEDB to connect to an instance of SQL Server: connection string method
The following Visual Basic code fragment shows how to use SQLOLEDB to connect to an instance or SQL Server: 

' Initialize variables.
Dim cn As New ADODB.Connection
Dim provStr As String

' Specify the OLE DB provider.
cn.Provider = "sqloledb"

' Specify connection string on Open method.
ProvStr = "Server=MyServer;Database=northwind;Trusted_Connection=yes"
cn.Open provStr

C. Using MSDASQL to connect to an instance of SQL Server
To use MSDASQL to connect to an instance of SQL Server, use the following types of connections.

The first type of connection is based on the ODBC API SQLConnect function. This type of connection is useful in situations where you do not want to code specific information about the data source. This may be the case if the data source could change or if you do not know its particulars. 

In the code fragment shown, the ConnectionTimeout method sets the connection time-out value to 100 seconds. Next, the data source name, user ID, and password are passed as parameters to the Open method of the Connection object, using an ODBC data source named MyDataSource that points to the northwind database on an instance of SQL Server. The sa login ID is provided as the second parameter and the password is the third parameter.

Dim cn As New ADODB.Connection

cn.ConnectionTimeout = 100
' DSN connection. You can use variables for the parameters.
cn.Open "MyDataSource", "sa", "MyPassword"
' Alternative syntax follows:
' cn.Open "DSN=DataSourceName;UID=sa;PWD=Password;"

cn.Close

The second type of connection is based on the ODBC API SQLDriverConnect function. This type of connection is useful in situations where you want a driver-specific connection string. To make a connection, use the Open method of the Connection object and specify the driver, server name, user ID, password, and database. You can also specify any other valid keywords to include in the connection string. For more information about the keyword list, see SQLDriverConnect. 

Dim cn As New ADODB.Connection

' Connection to SQL Server without using ODBC data source.
cn.Open "Driver={SQL Server};Server=Server1;Uid=SA;Pwd=;Database=northwind"

cn.Close