折騰了半天，其實比較簡單，程式碼如下，其中需要先新增引用
using System.Data.OracleClient;

        private void select()
         {
             string connString = "User Id=sh;Password=sh;Data Source=(DESCRIPTION = (ADDRESS_LIST= (ADDRESS = (PROTOCOL = TCP)(HOST =127.0.0.1)(PORT = 1521))) (CONNECT_DATA = (SERVICE_NAME = orcl)))"
 
;//本機資料庫地址
             此處可以寫在config檔案中，便於修改：（<add key="conn" value="User Id=sh;Password=sh;Data Source=(DESCRIPTION = (ADDRESS_LIST= (ADDRESS = (PROTOCOL = TCP)(HOST =127.0.0.1)(PORT = 1521))) (CONNECT_DATA = (SERVICE_NAME = orcl)))"/>）
             OracleConnection conn = new OracleConnection(connString);
             conn.Open();
             //取出表中欄位為PLACE的值，distinct過濾重複資料;
 

             string searchsql = "select distinct PLACE from TX_PERSON_CAR ";
             OracleCommand cmd = new OracleCommand(searchsql, conn);
             cmd.CommandType = CommandType.Text;
             //大容量資料，可以進行修改，使用DataSet和DataAdapter
             DataSet ds = new DataSet();
             OracleDataAdapter da = new
 
 OracleDataAdapter();
             da.SelectCommand = cmd;
             da.Fill(ds);
             DataTable dt = new DataTable();
             if (ds != null && ds.Tables.Count > 0)
                 dt = ds.Tables[0];
             int count = dt.Rows.Count;
             for (int i = 0; i < count; i++)
             {
                 string item = dt.Rows[i][0].ToString();//獲取資料庫中第i行第一列的值
                 camName.Items.Add(item);
             }
             camName.Items.Add("全部");
             this.camName.SelectedIndex = 0;
             this.camName.Text = "全部";
             conn.Close();
         }