问一下各位朋友，关于C#把在用DataGridView显示出来的数据源，显示在文本框的问题

主界面

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.SqlClient;

namespace frmMain

{

    public partial class frmMain : Form

    {



        public frmMain()

        {

            InitializeComponent();

        }

        #region 调用出手机信息维护系统

        private void ToolStripMenuItem_Click_1(object sender, EventArgs e)

        {

            mobileInfoVindicate mobileinfovindicate = new mobileInfoVindicate();

            mobileinfovindicate.Show();

            //

            mobileinfovindicate.MdiParent = this;

        }

        #endregion

        #region 退出系统

        private void tsdbt_Exit_Click(object sender, EventArgs e)

        {

            DialogResult result = MessageBox.Show("你确定要退出本程序吗？", "提示！", MessageBoxButtons.YesNo, MessageBoxIcon.Question);

            if (result == DialogResult.Yes)

            {

                this.Close();

            }

        }

        #endregion

    }

}

子窗体里的功能



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.SqlClient;

namespace frmMain

{

    public partial class mobileInfoVindicate : Form

    {

        public mobileInfoVindicate()

        {

            InitializeComponent();

        }

       

        /// <summary>

        /// 单击搜索所出来的数据

        /// </summary>

        /// <param name="sender"></param>

        /// <param name="e"></param>

        private void blb_Beat_Click(object sender, EventArgs e)

        {



            const string sql = "Data Source=.;Initial Catalog=MobileDB;User Id=sa;Pwd=sasa";

            SqlConnection conn = new SqlConnection(sql);

            string sqlOne = string.Format("select * from Mobile where Brand like'%{0}%'", txt_Input.Text);

            SqlCommand comm = new SqlCommand(sqlOne, conn);

            DataSet dst = new DataSet("MobileDB");

            SqlDataAdapter dataa = new SqlDataAdapter(comm);

            dataa.Fill(dst, "MobileInfo");

            dtgv_Tools.DataSource = dst.Tables["MobileInfo"];



            

        }



        #region 退出手机维护界面

        private void tsdbt_Exit_Click_1(object sender, EventArgs e)

        {



            DialogResult result = MessageBox.Show("确定要退出界面吗？", "aa", MessageBoxButtons.YesNo, MessageBoxIcon.Question);

            if (result == DialogResult.Yes)

            {

                this.Close();

            }

        }

        #endregion





    }

}