在C#中使用IDataReader读取dbf文件

发布于 2024-11-19 07:16:27 字数 699 浏览 2 评论 0原文

我正在尝试使用 OleDb 使用数据读取器读取 .dbf 文件，如下所示：

const string OleDbConnectionString =
    @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\mydbase;Extended Properties=dBASE IV;";
    var connection = new OleDbConnection(OleDbConnectionString);
    connection.Open();

    var command = new OleDbCommand("select * from my.dbf", connection);

    reader = command.ExecuteReader();
    Console.WriteLine(reader.Read()); // true
    Console.WriteLine(reader[0].ToString()); // exception

异常是 InvalidCastException 类型，并表示：无法从 System.__ComObject 转换为 IRowset。当我尝试使用 OleDbAdapter 填充表格时，一切正常。
如何使用 IDataReader 读取 .dbf 文件？

原文

I'm trying to read .dbf file with datareader using OleDb like this:

const string OleDbConnectionString =
    @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\mydbase;Extended Properties=dBASE IV;";
    var connection = new OleDbConnection(OleDbConnectionString);
    connection.Open();

    var command = new OleDbCommand("select * from my.dbf", connection);

    reader = command.ExecuteReader();
    Console.WriteLine(reader.Read()); // true
    Console.WriteLine(reader[0].ToString()); // exception

The exception is of InvalidCastException type and says: Unable to case from System.__ComObject to IRowset.
When I tried to use OleDbAdapter to fill a table everything worked fine.
How do I read .dbf file using IDataReader?

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荒岛晴空 2024-11-26 07:16:27

我认为您的路径可能是错误的，因为您在连接字符串中有“C:\mybase”，然后添加“my.dbf”，加起来为“C:\mybasemy.dbf”。

我将提供如何使用数据集而不是阅读器打开和读取 dbf 的代码。

string oledbConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\spcs\;Extended Properties=dBASE IV;User ID=Admin;Password=";

        OleDbConnection oledbConnection = new OleDbConnection(oledbConnectionString);

        string oledbQuery = @"SELECT * FROM KUND";

        try
        {
            OleDbCommand oledbCommand = new OleDbCommand(oledbQuery, oledbConnection);

            OleDbDataAdapter oledbAdapter = new OleDbDataAdapter(oledbCommand);

            DataSet oledbDataset = new DataSet();

            oledbAdapter.FillSchema(oledbDataset, SchemaType.Mapped);

            oledbConnection.Open();

            oledbAdapter.Fill(oledbDataset);

            foreach (DataRow row in oledbDataset.Tables[0].Rows)
            {
                System.Diagnostics.Trace.WriteLine(row[0].ToString());
            }
        }
        catch (Exception ex)
        {
            // Do something with ex
        }

I think your path might be wrong since you have "C:\mybase" in the connectionstring and then add "my.dbf" which adds up to "C:\mybasemy.dbf".

Ill provide code how i open and read a dbf using a dataset instead of a reader.

string oledbConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\spcs\;Extended Properties=dBASE IV;User ID=Admin;Password=";

        OleDbConnection oledbConnection = new OleDbConnection(oledbConnectionString);

        string oledbQuery = @"SELECT * FROM KUND";

        try
        {
            OleDbCommand oledbCommand = new OleDbCommand(oledbQuery, oledbConnection);

            OleDbDataAdapter oledbAdapter = new OleDbDataAdapter(oledbCommand);

            DataSet oledbDataset = new DataSet();

            oledbAdapter.FillSchema(oledbDataset, SchemaType.Mapped);

            oledbConnection.Open();

            oledbAdapter.Fill(oledbDataset);

            foreach (DataRow row in oledbDataset.Tables[0].Rows)
            {
                System.Diagnostics.Trace.WriteLine(row[0].ToString());
            }
        }
        catch (Exception ex)
        {
            // Do something with ex
        }

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彩扇题诗 2024-11-26 07:16:27

好的，尝试使用 GetString：

const string OleDbConnectionString =
@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\mydbase;Extended Properties=dBASE IV;";
OleDbConnection connection = new OleDbConnection(OleDbConnectionString);
connection.Open();

OleDbCommand command = new OleDbCommand("select * from my.dbf", connection);

OleDbDataReader reader = command.ExecuteReader();
Console.WriteLine(reader.Read()); // true
Console.WriteLine("{0}", reader.GetString(0)); // exception

Okay, try using GetString:

const string OleDbConnectionString =
@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\mydbase;Extended Properties=dBASE IV;";
OleDbConnection connection = new OleDbConnection(OleDbConnectionString);
connection.Open();

OleDbCommand command = new OleDbCommand("select * from my.dbf", connection);

OleDbDataReader reader = command.ExecuteReader();
Console.WriteLine(reader.Read()); // true
Console.WriteLine("{0}", reader.GetString(0)); // exception

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