C# Jet byte[]

你可以使用以下代码将 Jet 数据库中的表转换为 byte[] 数组：

public byte[] ConvertJetTableToByteArray(string connectionString, string tableName)
{
    byte[] byteArray = null;
    using (OleDbConnection connection = new OleDbConnection(connectionString))
    {
        connection.Open();
        
        // 获取表的记录数
        OleDbCommand command = new OleDbCommand($"SELECT COUNT(*) FROM [{tableName}]", connection);
        int recordCount = (int)command.ExecuteScalar();
        
        // 获取表的字段数和字段类型
        command.CommandText = $"SELECT TOP 1 * FROM [{tableName}]";
        DataTable schemaTable = new DataTable();
        OleDbDataAdapter dataAdapter = new OleDbDataAdapter(command);
        dataAdapter.FillSchema(schemaTable, SchemaType.Source);
        int fieldCount = schemaTable.Columns.Count;
        List<Type> fieldTypes = new List<Type>();
        for (int i = 0; i < fieldCount; i++)
        {
            fieldTypes.Add(schemaTable.Columns[i].DataType);
        }

        // 构造 byte[] 数组
        byteArray = new byte[4 + fieldCount * 2 + recordCount * fieldCount * 2];
        BinaryWriter binaryWriter = new BinaryWriter(new MemoryStream(byteArray));
        binaryWriter.Write(recordCount);
        binaryWriter.Write(fieldCount);
        for (int i = 0; i < fieldCount; i++)
        {
            binaryWriter.Write((short)Type.GetTypeCode(fieldTypes[i]));
            binaryWriter.Write((short)Encoding.Unicode.GetByteCount(schemaTable.Columns[i].ColumnName));
            binaryWriter.Write(Encoding.Unicode.GetBytes(schemaTable.Columns[i].ColumnName));
        }
        command.CommandText = $"SELECT * FROM [{tableName}]";
        OleDbDataReader reader = command.ExecuteReader();
        while (reader.Read())
        {
            for (int i = 0; i < fieldCount; i++)
            {
                if (reader.IsDBNull(i))
                {
                    binaryWriter.Write((short)0);
                }
                else
                {
                    object fieldValue = reader.GetValue(i);
                    byte[] fieldBytes = null;
                    switch (Type.GetTypeCode(fieldTypes[i]))
                    {
                        case TypeCode.Boolean:
                            fieldBytes = BitConverter.GetBytes((bool)fieldValue);
                            break;
                        case TypeCode.Byte:
                            fieldBytes = new byte[] { (byte)fieldValue };
                            break;
                        case TypeCode.Char:
                            fieldBytes = Encoding.Unicode.GetBytes(new char[] { (char)fieldValue });
                            break;
                        case TypeCode.DateTime:
                            fieldBytes = BitConverter.GetBytes(((DateTime)fieldValue).ToOADate());
                            break;
                        case TypeCode.Decimal:
                            fieldBytes = ((decimal)fieldValue).ToByteArray();
                            break;
                        case TypeCode.Double:
                            fieldBytes = BitConverter.GetBytes((double)fieldValue);
                            break;
                        case TypeCode.Int16:
                            fieldBytes = BitConverter.GetBytes((short)fieldValue);
                            break;
                        case TypeCode.Int32:
                            fieldBytes = BitConverter.GetBytes((int)fieldValue);
                            break;
                        case TypeCode.Int64:
                            fieldBytes = BitConverter.GetBytes((long)fieldValue);
                            break;
                        case TypeCode.Single:
                            fieldBytes = BitConverter.GetBytes((float)fieldValue);
                            break;
                        case TypeCode.String:
                            fieldBytes = Encoding.Unicode.GetBytes((string)fieldValue);
                            break;
                    }
                    binaryWriter.Write((short)fieldBytes.Length);
                    binaryWriter.Write(fieldBytes);
                }
            }
        }
        binaryWriter.Close();
    }
    return byteArray;
}

在上面的代码中，我们首先打开 Jet 数据库连接，并获取目标表的记录数和字段信息。然后，我们使用 `BinaryWriter` 将表的记录和字段写入 `MemoryStream` 中，并将 `MemoryStream` 转换为 byte[] 数组并返回它。最后，我们关闭 `BinaryWriter` 和 `MemoryStream` 对象以释放资源。