SQL-Server ADO.NET单一查询

 promgram.cs

 

using System;
using System.Collections.Generic;
using System.Data;

using System.Data.SqlClient;

namespace ConsoleApp
{
    class Program
    {
        //链接字符串--链接数据库用
        private static readonly string connString = @"Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=StudentManger;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
        static void Main(string[] args)
        {
            //准备好SQL语句
            string sql = "select ClassName from StudentClass where ClassName=N'小程序'";

            //链接SQL数据查询
            SqlConnection conn = new SqlConnection(connString);//链接数据库(链接数据库实例)
            SqlCommand cmd = new SqlCommand(sql, conn);//发送sql命令
            conn.Open();//打开链接
           object result= cmd.ExecuteScalar();
            conn.Close();//关闭链接

            //展示数据
            Console.WriteLine("班级名称" + result.ToString());
            Console.Read();
        }
    }
}

StudentClass.cs

 

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApp
{
    /// <summary>
    /// 班级实体类--在数据库种表示为一行数据
    /// </summary>
   public class StudentClass
    {
       /// <summary>
       /// 班级ID
       /// </summary>
        public int ClassId { get; set; }
        /// <summary>
        /// 班级名称
        /// </summary>
        public  string ClassName { get; set; }
    }
}