C# 验证sql server数据库账号密码是否正确

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace Ex16_05
{
    public partial class Form1 : Form
    {
        public Form1（）
        {
            InitializeComponent（）;
        }
        public SqlConnection con = null;//实义数据库连接对象
        private void button1_Click（object sender EventArgs e）
        {
            if （textBox1.Text == ““）
            {
                MessageBox.Show（textBox1.Tag.ToString（）+“不能为空““提示“）;
                textBox1.Focus（）;
                return;
            }
            if （textBox2.Text == ““）
            {
                MessageBox.Show（textBox2.Tag.ToString（） + “不能为空“ “提

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2010-04-06 13:10  Ex16_05\
     文件         910  2007-07-11 11:34  Ex16_05.sln
     文件       27648  2007-07-11 11:34  Ex16_05.suo
     目录           0  2010-04-06 13:10  Ex16_05\bin\
     目录           0  2010-04-06 13:10  Ex16_05\bin\Debug\
     文件       24576  2007-07-11 11:34  Ex16_05\bin\Debug\Ex16_05.exe
     文件       26112  2007-07-11 11:34  Ex16_05\bin\Debug\Ex16_05.pdb
     文件        5658  2007-07-11 11:34  Ex16_05\bin\Debug\Ex16_05.vshost.exe
     文件        3221  2007-07-11 11:34  Ex16_05\Ex16_05.csproj
     文件        2227  2007-07-11 11:34  Ex16_05\Form1.cs
     文件        8105  2007-07-11 11:34  Ex16_05\Form1.Designer.cs
     文件        5814  2007-07-11 11:34  Ex16_05\Form1.resx
     目录           0  2010-04-06 13:10  Ex16_05\obj\
     目录           0  2010-04-06 13:10  Ex16_05\obj\Debug\
     文件         842  2007-07-11 11:34  Ex16_05\obj\Debug\Ex16_05.csproj.GenerateResource.Cache
     文件       24576  2007-07-11 11:34  Ex16_05\obj\Debug\Ex16_05.exe
     文件         180  2007-07-11 11:34  Ex16_05\obj\Debug\Ex16_05.Form1.resources
     文件       26112  2007-07-11 11:34  Ex16_05\obj\Debug\Ex16_05.pdb
     文件         180  2007-07-11 11:34  Ex16_05\obj\Debug\Ex16_05.Properties.Resources.resources
     目录           0  2010-04-06 13:10  Ex16_05\obj\Debug\TempPE\
     文件         268  2007-07-11 11:34  Ex16_05\obj\Ex16_05.csproj.FileList.txt
     文件         466  2007-07-11 11:34  Ex16_05\Program.cs
     目录           0  2010-04-06 13:10  Ex16_05\Properties\
     文件        1162  2007-07-11 11:34  Ex16_05\Properties\AssemblyInfo.cs
     文件        2868  2007-07-11 11:34  Ex16_05\Properties\Resources.Designer.cs
     文件        5612  2007-07-11 11:34  Ex16_05\Properties\Resources.resx
     文件        1090  2007-07-11 11:34  Ex16_05\Properties\Settings.Designer.cs
     文件         249  2007-07-11 11:34  Ex16_05\Properties\Settings.settings