Sql query not working with MS Access 2007 database

Hi Freinds

below sql query is working nicely when using sql database but with ms acess database this query show msg "

System.Data.OleDb.OleDbException: 'Invalid SQL statement; expected 'DELETE', 'INSERT', 'PROCEDURE', 'SELECT', or 'UPDATE'.'"

please help me to come out from this issue

private void btnSAVE_Click(object sender, EventArgs e)
{
using (OleDbConnection conn = new OleDbConnection(conString))
{
conn.Open();
OleDbCommand cmd = conn.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "IF EXISTS(select * from tblSUPPLIER where SUPPLIERID='" + txtSUPPLIERID.Text + "') update tblSUPPLIER set [SUPPLIERNAME] = '" + txtSUPPLIERNAME.Text + "' where SUPPLIERID = '" + txtSUPPLIERID.Text + "' ELSE insert into tblSUPPLIER (SUPPLIERNAME) values('" + txtSUPPLIERNAME.Text + "')";
cmd.ExecuteNonQuery();
conn.Close();
}
MessageBox.Show("Added successfully!");
}