当前工作区域中未打开任何表 [英] No table is open in the current work area

问题描述

当尝试使用下面的代码在现有DBF文件上创建CDX文件时，出现一个异常，提示"No table is open in the current work area".

While trying to create CDX file on existing DBF file using below code, I'm getting an exception saying "No table is open in the current work area".

语言-C#

异常详细信息-

Message - No table is open in the current work area.
Source - Microsoft OLE DB Provider for Visual FoxPro

下面是代码段:

     public void CreateIndex()
    {
        var cdxExpressions = new List<CDXExpression> {
            new CDXExpression { expression = "ENTRY_DATE", name = "cdx_p1"},
            new CDXExpression { expression = "ENTRY_CODE", name = "cdx_p2"},
            new CDXExpression { expression = "Month", name = "cdx_p3"},
            new CDXExpression { expression = "Year", name = "cdx_p4"},
            new CDXExpression { expression = "Company", name = "cdx_p5"}
        };

        string dbfFile = ConfigurationManager.AppSettings["DBFFileLocation"];
        string connectionString = @"Provider=VFPOLEDB.1;Data Source=" + dbfFile + ";Extended Properties=dBASE IV;";
        OleDbConnection connection = new OleDbConnection(connectionString);

        var queries = DBFQuery.CreateCDXQueries(cdxExpressions, dbfFile);

        connection.Open();
        try
        {
            foreach (var qry in queries)
            {
                OleDbParameter script = new OleDbParameter("script", qry);
                OleDbCommand dbfCommand = connection.CreateCommand();
                dbfCommand.CommandType = CommandType.StoredProcedure;
                dbfCommand.CommandText = "ExecScript";
                //dbfCommand.Connection.Open();
                dbfCommand.Parameters.Add(script);
                dbfCommand.ExecuteNonQuery();
            }
        }
        catch (Exception ex)
        {
            // I should Open the DBF/Table in the current work area to avoid the exception
        }
        connection.Close();
    }

如何在c#中打开DBF文件以避免出现异常当前工作区中没有表打开"，也对Visual FoxPro使用Microsoft OLE DB Provider

How to open DBF file in c# to avoid exception "No table is open in the current work area", also using Microsoft OLE DB Provider for Visual FoxPro

推荐答案

这个与CDXExpression列表一起存在:

This one is with your CDXExpression list:

public void CreateIndex()
{
    var cdxExpressions = new List<CDXExpression> {
            new CDXExpression { expression = "ENTRY_DATE", name = "cdx_p1"},
            new CDXExpression { expression = "ENTRY_CODE", name = "cdx_p2"},
            new CDXExpression { expression = "Month", name = "cdx_p3"},
            new CDXExpression { expression = "Year", name = "cdx_p4"},
            new CDXExpression { expression = "Company", name = "cdx_p5"}
        };

    var myCode = "use sample exclusive\n" +
          string.Join("\n", cdxExpressions.Select(e => $"index on {e.expression} tag {e.name}")) +
          "\nuse";

    string dbfFile = ConfigurationManager.AppSettings["DBFFileLocation"];
    string connectionString = @"Provider=VFPOLEDB;Data Source=" + dbfFile;

    using (OleDbConnection connection = new OleDbConnection(connectionString))
    {
        OleDbCommand cmd = connection.CreateCommand();
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.CommandText = "ExecScript";
        OleDbParameter parm = cmd.CreateParameter();
        parm.OleDbType = OleDbType.Char;
        cmd.Parameters.Add(parm);
        parm.Value = myCode;
        try
        {
            connection.Open();
            cmd.ExecuteNonQuery();
        }
        catch (Exception ex)
        {
            // ...
        }
    }
}

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