using System;
using System.Collections.Generic;
using
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient ;

namespace connection对象
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (textBox1.Text == "")
            {
                MessageBox.Show("请输入要连接的数据库的名称");
            }
            else
            {
                try
                {
                   string  strConn = " Data Source =(local);";//本地的数据库
                   strConn += textBox1.Text.Trim();
                    strConn += "integrated security=true;";//windows身份验证

                    SqlConnection conn = new SqlConnection(strConn);
                    conn.Open();
                    if (conn.State == ConnectionState.Open)
                    {
                        label2.Text = "数据库【" + textBox1.Text.Trim() + "】已经连接并打开";
                    }
                }
                catch
                {
                    MessageBox.Show("连接数据库失败");
                }
            }
        }
    }
}

string connestring = "Data Source=WIN-08OC9UFPA79;Initial Catalog=school1;Integrated Security=True";
            SqlConnection connection = new SqlConnection(connestring);
链接数据库的两句代码，自己参考参考

string  strConn = " Data Source =(local);";//本地的数据库
                   strConn += "initial catalog="+textBox1.Text.Trim()+";";//数据库名
                    strConn += "integrated security=true;";//windows身份验证

[ 本帖最后由 shangsharon 于 2013-5-28 10:00 编辑 ]

应该是二三楼的，我这个回复又水了，哈哈

string  strConn = " Data Source =.;";//本地的数据库
                   strConn += textBox1.Text.Trim();
                    strConn += "integrated security=true;";//windows身份验证

还是先看看怎样连数据库吧， strConn = " Data Source =(local);";//本地的数据库
                   strConn += textBox1.Text.Trim();
                    strConn += "integrated security=true;";//windows身份验证


仔细看看你的  strConn等于什么，

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