数据库CSV导出

            try            {                DataTable dt = DBUtil.GetData("select * from room");                int columns_count = dt.Columns.Count;                SaveFileDialog savefile = new SaveFileDialog();                savefile.Filter = "CSV格式（*.CSV）|*.CSV";                DialogResult flag = savefile.ShowDialog();                if (flag == DialogResult.OK)                {                    string filename = savefile.FileName;                    StringBuilder sb_head = new StringBuilder();                    StringBuilder sb_rows = null;                    string head = string.Empty;                    string rows = string.Empty;                    FileStream fs = new FileStream(filename, FileMode.Create, FileAccess.Write);                    StreamWriter sw = new StreamWriter(fs, Encoding.Default);                    for (int i = 0; i < columns_count; i++)                    {                        sb_head.Append(dt.Columns[i] + ",");                    }                    head = sb_head.ToString();                    head = head.Substring(0, head.Length - 1);                    sw.WriteLine(head);                    for (int i = 0; i < dt.Rows.Count; i++)                    {                        sb_rows = new StringBuilder("");                        for (int a = 0; a < columns_count; a++)                        {                            sb_rows.Append(dt.Rows[i][a] + ",");                        }                        rows = sb_rows.ToString();                        rows = rows.Substring(0, rows.Length - 1);                        sw.WriteLine(rows);                    }                    sw.Close();                    fs.Close();                    MessageBox.Show("导出成功！");                }            }            catch (Exception)            {                MessageBox.Show("ERROR!");            }