C#连接数据库的方法

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace 登录
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnno_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void btnyes_Click(object sender, EventArgs e)
        {
            SqlConnectionStringBuilder scsb = new SqlConnectionStringBuilder();
            scsb.DataSource = "127.0.0.1";
            scsb.UserID = "sa";
            scsb.Password = "123456";
            scsb.InitialCatalog = "studb";

            SqlConnection conn = new SqlConnection(scsb.ToString());//参数：连接数据库的字符串
            if(conn.State==System.Data.ConnectionState.Closed)//判断连接的开启状态
            conn.Open();
            string userid=txtUser.Text.Trim();
            string owd = txtPwd.Text.Trim();
            string strSQL = "select owd from userinfo where [userid]='"+userid+"'";
            SqlCommand comm = new SqlCommand(strSQL,conn);
            SqlDataReader dr = comm.ExecuteReader();
            if(dr.Read())
            {
                if ((string)dr["owd"] == owd)
                    MessageBox.Show("成功");
                else
                    MessageBox.Show("错误");
            }
            else
            {
                MessageBox.Show("不存在");
            }

        }
    }
}