標量變量未聲明

Question

protected void DropDownList8_SelectedIndexChanged(object sender, EventArgs e) 
{ 
    var connectionString = (ConfigurationManager.ConnectionStrings["Connection"].ConnectionString); 
    var updateCmd = "UPDATE [CarTab] SET Rent= 1 WHERE ([Model] = @Model)"; 
    using (SqlConnection connection = new SqlConnection(connectionString)) 
    { 
     SqlCommand command = new SqlCommand(updateCmd, connection); 
     command.Connection.Open(); 
     command.ExecuteNonQuery(); 
    } 
} 

錯誤：必須爲@Model聲明標量變量。 我應該刪除/添加那裏？無法弄清楚。 在此先感謝。

Answer 1

您可以

command.Parameters.AddWithValue("@Model", value); 

您完整的代碼

protected void DropDownList8_SelectedIndexChanged(object sender, EventArgs e) 
{ 
    var connectionString = (ConfigurationManager.ConnectionStrings["Connection"].ConnectionString); 
    var updateCmd = "UPDATE [CarTab] SET Rent= 1 WHERE ([Model] = @Model)"; 
    using (SqlConnection connection = new SqlConnection(
       connectionString)) 
    { 
     using(var command = new SqlCommand(updateCmd, connection)) 
     { 
      command.Parameters.AddWithValue("@Model", value); //Replace with your value 

      command.Connection.Open(); 
      command.ExecuteNonQuery(); 
     } 
    } 
} 

嘗試

Answer 2

您必須添加參數@Model，如：

updateCmd.Parameters.Add("@Model", SqlDbType.SomeType); 
    updateCmd.Parameters["@Model"].Value = something;