transaction的问题，多谢

[breadjyh]

public cnnMain As Data.OleDb.OleDbConnection '数据连接

Public Function f_ConnectDB() As Boolean '建立与数据库的连接
Try
cnnMain = New OleDb.OleDbConnection("Provider=Microsoft.Jet.Oledb.4.0;Data Source=db.mdb")
cnnMain.Open()
Return True
Catch ex As Exception
MsgBox(ex.ToString)
Return False
End Try
End Function

Dim l_cmm As OleDb.OleDbCommand
Dim l_tran As OleDb.OleDbTransaction
l_tran = cnnMain.BeginTransaction(IsolationLevel.ReadCommitted)
执行到此处提示cnnmain未打开...的错误信息，而实际上cnnmain已经打开（连接的是access数据库）

[brightheroes]

Function f_ConnectDB()在什么地方调用的？

[cancersyf]

是不是db.mdb被其它进程占用了而导致连接打开失败?

[jxyctian]

Dim myConnection As SqlConnection = New SqlConnection("Data Source=localhost;Initial Catalog=Northwind;Integrated Security=SSPI;")
myConnection.Open()

' Start a local transaction.
Dim myTrans As SqlTransaction = myConnection.BeginTransaction()

' Enlist the command in the current transaction.
Dim myCommand As SqlCommand = myConnection.CreateCommand()
myCommand.Transaction = myTrans
Try
myCommand.CommandText = "Insert into Region (RegionID, RegionDescription) VALUES (100, 'Description')"
myCommand.ExecuteNonQuery()
myCommand.CommandText = "Insert into Region (RegionID, RegionDescription) VALUES (101, 'Description')"
myCommand.ExecuteNonQuery()
myTrans.Commit()
Console.WriteLine("Both records are written to database.")
Catch e As Exception
Try
myTrans.Rollback()
Catch ex As SqlException
If Not myTrans.Connection Is Nothing Then
Console.WriteLine("An exception of type " & ex.GetType().ToString() & _

" was encountered while attempting to roll back the transaction.")
End If
End Try
Console.WriteLine("An exception of type " & e.GetType().ToString() & _
"was encountered while inserting the data.")
Console.WriteLine("Neither record was written to database.")
Finally
myConnection.Close()
End Try
連接到SQL 參考一下.