private void button1_Click(object sender, EventArgs e)
        {
           
            if (textBox1.Text == "")
            {
                MessageBox.Show("请输入要连接的数据库名称");
            }
            else
            {
                try
                {
                    string constr = "LENOVO-PC\\SQLEXPRESS; database=" + textBox1.Text.Trim() + ";uid=sa;pwd=111";

                    SqlConnection conn = new SqlConnection(constr);

                    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");
                }
            }