Question

下面是我用来连接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获取任何值。我可以看到有正确的行数，但是我一直得到一个InvalidOperationException（我是否使用GetValue（）或GetString（））说“行/列没有数据。”

        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（使用而不是处理你自己的连接

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");
   }

Answer 2

像这样修改你的代码：

using (OleDbConnection connection = new OleDbConnection(connectionString))
    {
        OleDbCommand command = new OleDbCommand(queryString, connection);
        connection.Open();

        using (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.
            }
        }
    }

从读取Access数据库的OleDbDataReader获取值

2 个答案: