c# - 从 OleDbDataReader 读取 Access 数据库取回值

Question

在它下面是我用来连接到 Access 数据库并从查询中提取值的代码。问题是..我无法从读者对象中取回任何值。我可以看到行数正确，但是我不断收到 InvalidOperationException(无论我使用 GetValue() 还是 GetString())说“行/列不存在数据。”

        System.Data.OleDb.OleDbConnection conn = new
        System.Data.OleDb.OleDbConnection();
        conn.ConnectionString = @"Provider=Microsoft Office 12.0 Access Database Engine OLE DB Provider;" +
                                @"Data source= C:\Users\nearod\Desktop\ImportDB.accdb";
        try
        {
            conn.Open();
            OleDbCommand cmd = new OleDbCommand("SELECT * FROM [SQL Agent Unique ID Test Load]", conn);

            OleDbDataReader reader = cmd.ExecuteReader();

            string companyCode = reader.GetValue(0).ToString();
            string agentId = reader.GetString(1);
            string firstName = reader.GetString(2);
            string lastName = reader.GetString(3);
            string nameSuffix = reader.GetString(4);
            string corporateName = reader.GetString(5);
            string entityType = reader.GetString(6);
            string obfSSN = reader.GetString(7);
            string obfFEIN = reader.GetString(8);
            string dummyIndicator = reader.GetString(9);
            // Insert code to process data.
        }
        catch (Exception ex)
        {
            MessageBox.Show("Failed to connect to data source");
        }
        finally
        {
            conn.Close();
        }

Answer 1

你必须像下面这样调用 Read 方法(使用 using 而不是自行处理连接

string connectionString = @"Provider=Microsoft Office 12.0 Access Database Engine OLE DB Provider;" + @"Data source= C:\Users\nearod\Desktop\ImportDB.accdb";

string queryString=  "SELECT * FROM [SQL Agent Unique ID Test Load]";
 try
     {
    using (OleDbConnection connection = new OleDbConnection(connectionString))
        {
            OleDbCommand command = new OleDbCommand(queryString, connection);
            connection.Open();
            OleDbDataReader reader = command.ExecuteReader();

            while (reader.Read())
            {
                string companyCode = reader.GetValue(0).ToString();
            string agentId = reader.GetString(1);
            string firstName = reader.GetString(2);
            string lastName = reader.GetString(3);
            string nameSuffix = reader.GetString(4);
            string corporateName = reader.GetString(5);
            string entityType = reader.GetString(6);
            string obfSSN = reader.GetString(7);
            string obfFEIN = reader.GetString(8);
            string dummyIndicator = reader.GetString(9);
            // Insert code to process data.
            }
            reader.Close();
        }
   }
catch (Exception ex)
   {
            MessageBox.Show("Failed to connect to data source");
   }