Foxpro:通过vfpoledb检查表是否存在

如果您有一个dbc文件,您可以查询它以查看表是否存在。

string dbc = "northwind.dbc";

using (OleDbConnection conn = new OleDbConnection(connectionString)) {
    DataTable dt = new DataTable();
    string sql = string.Format(@"SELECT * FROM {0} WHERE ALLTRIM(ObjectType) = 'Table' AND UPPER(ALLTRIM(ObjectName)) = '{1}'", dbc, tableName.ToUpper());
    OleDbDataAdapter da = new OleDbDataAdapter(sql, conn);
    da.Fill(dt);
    bool tableExists = dt != null && dt.Rows.Count == 1;
}

using (OleDbConnection conn = new OleDbConnection(connectionString)) {
    conn.Open();
    DataTable tables = conn.GetSchema("Tables");
    conn.Close();

    var tableExists = (from row in tables.AsEnumerable()
                        where row.Field<string>("Table_Name").Equals(tableName, StringComparison.CurrentCultureIgnoreCase)
                        select row.Field<string>("Table_Name")).FirstOrDefault() != null;
}

另外,如果您连接到的DBF表是“自由”表,而不是实际连接的“数据库”(.dbc)的一部分,那么您可以检查文件是否存在。。。比如C#via

if( File.Exists( PathToTheDatabaseDirectory + TableYouExpect + ".DBF" ))
   file is there
else
   file is missing

我不知道如何只使用SQL,但也许你可以使用 File.Exists Method 或者可以编写一些代码,使用OleDb类检查dbf是否存在:

private bool DbfExists(string dbfName, string connectionString)
{
    bool dbfExists = true;

    using(OleDbConnection conn = new OleDbConnection(connectionString))
    {
        string sql = string.Format("SELECT * FROM {0}", dbfName);

        using(OleDbCommand command = new OleDbCommand(sql, conn))
        {
            OleDbDataReader reader = null;

            try
            {
                conn.Open();
                reader = command.ExecuteReader();
            }
            catch(Exception ex)
            {
                dbfExists = false;
            }
            finally
            {
                conn.Close();
                reader = null;
            }
        }
    }

    return dbfExists;
}

我还没有试过编译这段代码,所以它可能需要调整一点。