Question

我收到以下错误

ExecuteNonQuery：尚未初始化Connection属性。

运行以下代码时

Private Sub btnUpdate_Click(sender As Object, e As EventArgs) Handles btnUpdate.Click

    Using con = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=E:\Comp-296\Project1\Project1\Game_time.mdb")

        Using cmd = New OleDbCommand("UPDATE User-scores SET User_Name = @User_Name Game_Name = @Game_Name Score = @Score, [Time/Date] = @dt")

            con.Open()
            cmd.Parameters.Add("@User_Name", OleDbType.VarWChar).Value = txtUser.Text
            cmd.Parameters.Add("@Game_Name", OleDbType.VarWChar).Value = txtGame.Text
            cmd.Parameters.Add("@Score", OleDbType.VarWChar).Value = txtScore.Text
            cmd.Parameters.Add("@dt", OleDbType.Date).Value = Convert.ToDateTime(txtDate.Text)

            cmd.ExecuteNonQuery()

            MessageBox.Show("Data Update successfully")
        End Using
    End Using

End Sub

我忘记在参数中添加一些内容吗？

Answer 1

您必须将连接作为参数传递给OledbCommand

只需使用以下代码

Using con = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=E:\Comp-296\Project1\Project1\Game_time.mdb") 

    Using cmd = New OleDbCommand("UPDATE [User-scores] SET [User_Name] = ?, [Game_Name] = ?, Score = ?, [Time/Date] = ? WHERE id = 1", con) 
        con.Open() 
        cmd.Parameters.Add("@p1", OleDbType.VarWChar).Value = txtUser.Text 
        cmd.Parameters.Add("@p2", OleDbType.VarWChar).Value = txtGame.Text 
        cmd.Parameters.Add("@p3", OleDbType.VarWChar).Value = txtScore.Text 
        cmd.Parameters.Add("@p4", OleDbType.Date).Value = Convert.ToDateTime(txtDate.Text) 

        cmd.ExecuteNonQuery() 

        MessageBox.Show("Data Update successfully") 
    End Using 
End Using

看起来您必须使用?标记将参数传递给OledbCommand （您的方法适用于SQLCommand）

详细了解Oledb Parameters

Answer 2

您忘记添加命令连接，更新cmd，添加如下所示的连接

 Using cmd = New OleDbCommand("UPDATE User-scores SET User_Name = @User_Name Game_Name = @Game_Name Score = @Score, [Time/Date] = @dt",con)

更新：更新COMMA更新

 @User_Name, Game_Name = @Game_NamE, Score = @Score

Answer 3

您尚未将命令与Connection相关联。代码不知道哪个连接（理论上你可能有几个）来运行命令。

您可以使用构造函数或属性将命令与特定连接相关联：

Using cmd = New OleDbCommand("UPDATE User-scores SET User_Name = @User_Name Game_Name = @Game_Name Score = @Score, [Time/Date] = @dt",con)

或者：

cmd.Connection = con

（在您声明cmd后的行上）

Answer 4

您可以使用CreateCommand创建连接创建命令。这样连接就已经与创建的命令相关联。但这意味着您必须在CommandText属性

上设置命令文本

Using con = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=E:\Comp-296\Project1\Project1\Game_time.mdb")

    Using cmd = con.CreateCommand()
        con.Open()
        cmd.CommandText = "UPDATE User-scores SET User_Name = @User_Name, Game_Name = @Game_Name, Score = @Score, [Time/Date] = @dt"
        cmd.Parameters.Add("@User_Name", OleDbType.VarWChar).Value = txtUser.Text
        cmd.Parameters.Add("@Game_Name", OleDbType.VarWChar).Value = txtGame.Text
        cmd.Parameters.Add("@Score", OleDbType.VarWChar).Value = txtScore.Text
        cmd.Parameters.Add("@dt", OleDbType.Date).Value = Convert.ToDateTime(txtDate.Text)

        cmd.ExecuteNonQuery()


        MessageBox.Show("Data Update successfully")
    End Using
End Using

ExecuteNonQuery：尚未初始化Connection属性

4 个答案: