adapter 从未被使用过

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;

namespace 专科医院门诊系统_眼科_
{

public partial class 挂号界面 : Form
{
    OleDbDataAdapter adapter;
    DataTable table = new DataTable();
    string str = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=E:\design\vc\project\专科医院门诊系统（眼科）\db1.accdb";
    OleDbConnection con = new OleDbConnection();
    public 挂号界面()
    {
        InitializeComponent();
        con.ConnectionString = str;
    }

    private void button1_Click(object sender, EventArgs e)
    {
        挂号缴费选择界面 frm = new 挂号缴费选择界面();
        frm.Show();
        Hide();
    }
    private void button2_Click(object sender, EventArgs e)
    {
        string a = textBox1 .Text ;
        string b = textBox2 .Text ;
        string c = textBox3 .Text ;
        string d = textBox4 .Text ;
        string f = textBox5 .Text ;
        string g = textBox6 .Text ;
        OleDbCommand cmd = new OleDbCommand (@"insert into [patient](ID,名字,年龄,性别,电话号码,科室) values('"+a +"','"+b +"','"+c +"','"+f +"','"+g +"')", con);
        con.Open();
        cmd.Connection = con;
        cmd .ExecuteNonQuery();
        con.Close();
    }
    private void button3_Click(object sender, EventArgs e)
    {
        textBox1.Text = textBox2.Text = textBox3.Text = textBox4.Text = textBox5.Text = string.Empty;
    }
    private void 挂号界面_Load(object sender, EventArgs e)
    {

    }
}

}

求大神看看怎么改吧

是啊，你的adapter根本就没有用

如果你没有使用过但是程序还能正常运行，说明它是多余的，直接删除就行了。