ConnectionString 属性尚未初始化

Question

public partial class User : Form
    {       
        public User()
        {
            InitializeComponent();
          
        }        public DataSet ds = new DataSet();
        SqlDataAdapter sda1 = null;        string username;
        string userpsw;
        string userlevel;        //编辑现有用户
        private void BT_edit_Click(object sender, EventArgs e)
        {
            
            sda1.Update(ds, "a");
            Databind();
        }
        //删除所选用户
        private void BT_delete_Click(object sender, EventArgs e)
        {
              
        }        //重载控件
        private void BT_refresh_Click(object sender, EventArgs e)
        {
                 //  刷新datagridview    把当前的form重新加载
            User_Load(sender, e);        }                //数据绑定方法        
        public void Databind()
        {
            SqlConnection scon1 = new SqlConnection("Data Source=acer-PC;Initial Catalog=cmis;Integrated Security=True;Pooling=False");
            string sqlconnet1 = "select [username] '名称',[userpsw] '密码',[userlevel] '等级' from [users]";
            SqlCommand scmd1 = new SqlCommand(sqlconnet1, scon1);
            sda1 = new SqlDataAdapter(scmd1);
            sda1.SelectCommand = scmd1;
            SqlCommandBuilder scb = new SqlCommandBuilder(sda1);
            
            sda1.InsertCommand = scb.GetInsertCommand();
            sda1.DeleteCommand = scb.GetDeleteCommand();
            sda1.UpdateCommand = scb.GetUpdateCommand();            try
            {
            scon1.Open();
            ds.Clear();
            sda1.Fill(ds, "a");
            this.DATA_user.DataSource = ds.Tables[0];            }
            catch (Exception ex)
                    {
                        MessageBox.Show("数据库异常");
                    }
            finally
            {
            scon1.Close();
            scon1.Dispose();
            scmd1.Dispose();
            sda1.Dispose();            }
        }        private void User_Load(object sender, EventArgs e)
        {
            Databind();
        }

Answer 1

config 文件<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <configSections>
    </configSections>
    <connectionStrings>
        <add name="MIS.Properties.Settings.cmisConnectionString" connectionString="Data Source=acer-PC;Initial Catalog=cmis;Integrated Security=True;Pooling=False"
            providerName="System.Data.SqlClient" />
    </connectionStrings>
</configuration>

Answer 2

SqlCommand scmd1 = new SqlCommand(sqlconnet1);//下面行添加 ,scon1
  sda1 = new SqlDataAdapter(scmd1,scon1);
  sda1.SelectCommand = scmd1;
  SqlCommandBuilder scb = new SqlCommandBuilder(sda1);

Answer 3

我把 conn.dispose()；修改了。   解决了。