C# 文件写入(StreamWriter)，保存文件对话框(SaveFileDialog)

private void btbExport_Click(object sender, EventArgs e)
{
#region 选择保存文件
string fileName = string.Empty;// 保存的文件名
//让用户选择 要保存的文件路径
using (SaveFileDialog sfd = new SaveFileDialog())
{
if (sfd.ShowDialog() != DialogResult.OK)
{
return;
}
fileName = sfd.FileName;
}
#endregion

// 查询数据数据，写入数据
string connStr = ConfigurationManager.ConnectionStrings["sqlConn"].ConnectionString;

using (SqlConnection conn =new SqlConnection(connStr))
{
using (SqlCommand cmd =conn.CreateCommand())
{
conn.Open();

cmd.CommandText = "select AreaId, AreaName, AreaPid from [dbo].[AreaFull]";

using (SqlDataReader reader =cmd.ExecuteReader())
{
string tempLine = string.Empty;
using (StreamWriter writer =new StreamWriter(fileName))
{
while (reader.Read())
{
tempLine = reader["AreaId"] + "," +
reader["AreaName"] + "," +
reader["AreaPId"];
writer.WriteLine(tempLine);//写入文本文件
}
}

}
}
}
}