//连接字符串
        ConnectionStr = @"Data Source=.\SQLEXPRESS;AttachDbFilename=D:\360data\重要数据\我的文档\用户注册信息.mdf;
        Integrated Security=True;Connect Timeout=30;User Instance=True";
        //创建连接对象
        SqlConnection sqlCon = new SqlConnection(ConnectionStr);

        //建立插入命令字符串
        insertStr = "INSERT INTO 注册信息保存 (username,password,e-mail) VALUES ('"
            + TextBox1.Text + "','" + TextBox2.Text
            + "','"+TextBox4.Text+"')";
        try
        {
            //打开数据
            sqlCon.Open();
            if (sqlCon.State == ConnectionState.Open)
            {
                //创建命令对象
                SqlCommand sqlComm = new SqlCommand(insertStr, sqlCon);

               
            }
        }
        catch
        {
            if (sqlCon.State != ConnectionState.Open)
            {

            }
        }
        finally
        {
            //关闭数据库
            sqlCon.Close();
        }

catch (System.Exception ex)
     {                     
           MessageBox.Show(ex.Message);                 
      }

------解决方案--------------------
探讨

        insertStr = "INSERT INTO 注册信息保存 (username,password,e-mail) VALUES ('"
            + TextBox1.Text + "','" + TextBox2.Text
            + "','"+TextBox4.Text+"')";