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!");
}