2

我正在尝试将一些示例数据插入到 sql server 中。

我正在使用 Visual Basic 2010 Express。

这是代码：

Public Sub insert()

    Dim myconnect As New SqlClient.SqlConnection
    myconnect.ConnectionString = "Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\DATABASE_NUOVO.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True"


    Dim mycommand As SqlClient.SqlCommand = New SqlClient.SqlCommand()
    mycommand.Connection = myconnect
    mycommand.CommandText = "INSERT INTO utenti (nome) VALUES ('mario')"
    myconnect.Open()

    Try
        mycommand.ExecuteNonQuery()
    Catch ex As System.Data.SqlClient.SqlException
        MsgBox(ex.Message)
    End Try
    myconnect.Close()
    MsgBox("Success")

End Sub

代码似乎运行正确，但是当我在运行调试后查看数据库时，我没有看到示例数据。

哪里有问题？

谢谢

4

3 回答 3

6

As I've said before on this site - the whole User Instance and AttachDbFileName= approach is flawed - at best! Visual Studio will be copying around the .mdf file and most likely, your INSERT works just fine - but you're just looking at the wrong .mdf file in the end!

If you want to stick with this approach, then try putting a breakpoint on the myConnection.Close() call - and then inspect the .mdf file with SQL Server Mgmt Studio Express - I'm almost certain your data is there.

The real solution in my opinion would be to

  1. install SQL Server Express (and you've already done that anyway)

  2. install SQL Server Management Studio Express

  3. create your database in SSMS Express, give it a logical name (e.g. Database_Nuovo)

  4. connect to it using its logical database name (given when you create it on the server) - and don't mess around with physical database files and user instances. In that case, your connection string would be something like:

    Data Source=.\\SQLEXPRESS;Database=Database_Nuovo;Integrated Security=True

    and everything else is exactly the same as before...

Also: check what the value of the Copy to Output Directory property is on your DATABASE_NUOVO.mdf file in the App_Data directory (find it inside your Visual Studio Solution Explorer).

What might happen (and does, more often than not):

  • when Visual Studio starts your app for debugging, it copies Database_Nuovo.mdf to the output directory where the app is running (your .\debug\bin directory)
  • your INSERT then runs against this copy of the .mdf file and works just fine
  • you stop debugging and go check the database file again - but this time, you're looking at the Database_Nuovo.mdf in the App_Data directory --> and of course your inserted data isn't there since it was inserted into a different file!
于 2013-01-02T20:46:44.070 回答
2

尝试更改Try..Catch代码以处理更多错误类型，而不仅仅是 SqlExceptions。像这样：

    Try
        mycommand.ExecuteNonQuery()
    Catch ex As System.Data.SqlClient.SqlException
        MsgBox(ex.Message, , "Sql Exception")
    Catch ex As System.Exception
        MsgBox(ex.Message, , "General Exception")
    End Try

SqlExceptions 不是这里唯一可以抛出的异常。

于 2013-01-02T19:32:55.933 回答
0

试试吧。。

Dim con As New SqlConnection
Dim cmd As New SqlCommand
Try
con.ConnectionString = "Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\DATABASE_NUOVO.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True" //check your connection string carefully whether it points right directory
con.Open()
cmd.Connection = con
cmd.CommandText = "INSERT INTO table([field1], [field2]) VALUES([Value1], [Value2])" //make sure here your table and column name is exactly like as your database
cmd.ExecuteNonQuery()

Catch ex As Exception
MessageBox.Show("Error while inserting record on table...");
Finally
con.Close()
End Try
于 2013-01-02T19:47:20.563 回答