Update sql server database from excel sheet

SqlConnection strConnection = new SqlConnection(ConfigurationSettings.AppSettings["ConnectionString"]);

strConnection.Open();

string filepath = textBox1.Text;

string excelConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + filepath + ";Extended Properties=Excel 12.0;";

OleDbConnection excelConnection = new OleDbConnection(excelConnectionString);

excelConnection.Open();

OleDbDataAdapter da = new OleDbDataAdapter("Select column1 from [Sheet1$]", excelConnection);

Thread.Sleep(2000);

da.Fill(dt);

for (int i = 0; i < dt.Rows.Count; i++)

{

sqlcommand cmd= new sqlcommand("insert into tablename(column1) values(dt.rows[i][0].tostring())",con)

con.open();

cmd.executenonquery();

cmd.close();

}