数据库

 public string connectionString = "Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.24.**)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=orcl)));User Id=***;Password=***;";

        public OracleConnection conn ;//创建一个新连接
        public Form1()
        {
            InitializeComponent();

        }
   
        private void button1_Click(object sender, EventArgs e)
        {
              conn = new OracleConnection(connectionString);//创建一个新连接


           
            try
            {
                conn.Open();
                textBox1.Text = "数据库连接成功";
                Console.WriteLine(e.ToString());
                 
            }
            catch (System.Exception ex)
            {
                Console.Write(ex.Message);
                MessageBox.Show("未能连接到数据库");
                 
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            if (conn.State != ConnectionState.Open)
                conn.Open();
            DataSet ds = new DataSet();
            string sql = "select createuser from mpplantasktypewithstate";
            OracleCommand cmd = new OracleCommand(sql, conn);

            OracleDataAdapter da = new OracleDataAdapter(cmd);
            da.Fill(ds);
           int x=  ds.Tables[0].Rows.Count;
            string s = ds.Tables[0].Rows[11]["createuser"].ToString();
            textBox1.Text = x.ToString();
            textBox2.Text = s;
            
        }

      找到oracle安装目录下的Oracle.DataAccess.dll（ 不是本机的会出错），添加引用，再引用System.Data.dll，using Oracle.DataAccess.Client;using System.Data;