DBHelper.cs（c#）完

//需要导入命名空间

   using System.Data;
   using System.Data.SqlClient;

public class DBHelper
    {
        //创建链接字符串
        public static string str = "server=.;database=数据库名称;Integrated Security=true";
        public static SqlConnection conn = null;
        /*精彩活动要传的信息*/
        public static string wonderfulActivity = null;//保存精彩活动的名称
        public static string ActivityAutor=null;//保存精彩活动的作者
        public static string dateTime = null;//保存精彩活动上传的时间
        //增删改
        public static Boolean NonQuery(string sql)
        {
            conn = new SqlConnection(str);
            conn.Open();
            SqlCommand comm = new SqlCommand(sql,conn);
            int num = comm.ExecuteNonQuery();
            conn.Close();
            return num > 0;
        }

        //查询
        public static SqlDataReader Query(string sql)
        {
            conn = new SqlConnection(str);
            conn.Open();
            SqlCommand comm = new SqlCommand(sql, conn);
            return comm.ExecuteReader(CommandBehavior.CloseConnection);
        }
       
        //聚合函数（适用于查询某一个指定的字段信息）
        public static Object Scalar(string sql)
        {
            conn = new SqlConnection(str);
            conn.Open();
            SqlCommand comm = new SqlCommand(sql, conn);
            object obj = comm.ExecuteScalar();
            return obj;
        }
    }