using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SqlClient;

namespace Demp13
{
    class Program
    {
        static void Main(string[] args)
        {
            //1.創建連接字符串
            string str = "server=.;database=MySchool;uid=sa;pwd=密碼
 
";
            // string str = "Data Source=.;Initial Catalog=MySchool;User ID=sa;Password=accp";
            //2.創建connection對象
            SqlConnection conn = new SqlConnection(str);
            try
            {
                //3.打開鏈接
                conn.Open();
                Console.WriteLine("打開鏈接成功
 
");
                //4.準備sql語句，創建command對象，並執行sql語句
                Console.WriteLine("請輸入用戶名");
                string name = Console.ReadLine();
                Console.WriteLine("請輸入密碼");
                string pwd = Console.ReadLine();

                string sql = "select COUNT(*) from admin where loginId=‘
 
"+name+"‘ and loginPwd=‘"+pwd+"‘";
                SqlCommand cmd = new SqlCommand(sql,conn);
                //5.執行sql語句，得到返回結果
               int r= Convert.ToInt32(cmd.ExecuteScalar());
               if (r > 0)
               {
                   Console.WriteLine("登陸成功");
               }
               else {
                   Console.WriteLine("登陸失敗");
               }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            finally {
                //4.關閉鏈接
                conn.Close();
                Console.WriteLine("關閉鏈接成功");
            }
        }
    }
}

C#與SQL Server數據庫連接