Code

  <asp:Button ID="Button4" runat="server" Text="执行" Width="80px" /><br />
  <asp:TextBox ID="TextBox2" runat="server" Height="189px" TextMode="MultiLine" Width="98%"></asp:TextBox>
        <div style=" height:300px; border-right: silver 1px solid; border-top: silver 1px solid; border-left: silver 1px solid; width: 98%; border-bottom: silver 1px solid;">
        <asp:GridView ID="GridView1" runat="server">
        
        </asp:GridView>
        </div>

Code
 /// <summary>
    /// 执行
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void Button4_Click(object sender, EventArgs e)
    {
        DataSet ds= Get(this.TextBox2.Text.Trim());

        this.GridView1.DataSource = ds.Tables[0];
        GridView1.DataBind();
    }

    private DataSet Get(string sql)
    {
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            DataSet ds = new DataSet();
            try
            {
                connection.Open();
                SqlDataAdapter command = new SqlDataAdapter(SQLString, connection);
                command.Fill(ds, "ds");
            }
            catch (System.Data.SqlClient.SqlException ex)
            {
                throw new Exception(ex.Message);
            }
            return ds;
        }
    }