procedure DBConnect accepts one parameter, the connection string, and thereby allows us to open different databases based on the connection string that is passed to DBConnect.
A SqlConnection object represents a unique session to a SQL Server data source, and it is used together with a SqlDataAdapter and a SqlCommand to increase performance when connecting to a Microsoft SQL Server database.
•First, we set the variable SQLConn to a SQLConnection, and use the connection string that is passed to the procedure
•Next, we open the connection with the Open command
Closing a Database Connection
When a SqlConnection goes out of scope, it won't be closed, so we have to explicitly close the connection by calling Close or Dispose. Close and Dispose will both close a connection to an open database;however, Close is the preferred method of closing any open connection.
The code shown below in Listing 2 can be used to close a database connection.
Listing 2: Closing a Database Connection
Public Sub DBDisconnect(ByRef errorParms As Object)
Try
SqlConn.Close()
SqlConn = Nothing
SqlCmd = Nothing
Catch
' Return the error to the calling program.
errorParms(0) = 999
errorParms(1) = Err.Description
errorParms(2) =
System.Reflection.MethodBase.
GetCurrentMethod.Name
End Try
End Sub
The code in Listing 2 closes the database connection and sets the connection and the command objects to nothing, therefore, releasing the resources. Managing database connections is an important part of a good data access framework.
In the next section, we will develop the code that we will use to select records in Coding Briefs.
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