C# winfrom DBHelper 数据库访问类

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

namespace AntiSlipSys
{
    public class DBHelper
    {
        //数据库连接以及增删改查
        static String conn = "Data Source=.;Initial Catalog=AntiSlipSys;Integrated Security=True";//根据项目修改连接字符串

        SqlConnection comm = new SqlConnection(conn);
        SqlCommand command = null;
        SqlDataReader reader = null;
        DataSet ds = null;
        SqlDataAdapter adapter = null;
        
        #region 打开数据库连接

        public void OpenConnection()
        {
            try
            {
                comm.Open();
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }
        }

        #endregion

        #region 关闭数据库连接

        public void CloseConnection()
        {
            try
            {
                if (reader != null)
                {
                    reader.Close();
                }
                if (comm != null)
                {
                    comm.Close();
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }
        }

        #endregion

        #region 数据查询
        /// <summary>
        /// 连接式查询
        /// </summary>
        /// <param name="sql">查询的sql语句</param>
        /// <returns>查询所返回的DataReader对象</returns>
        public SqlDataReader Query(string sql)
        {
            this.OpenConnection();
            command = new SqlCommand(sql,comm);
            reader = command.ExecuteReader();
            return reader;
        }

        #endregion

        #region 数据更新操作
        /// <summary>
        /// 用户执行数据的更新操作 I：更新 D：删除 U：修改
        /// </summary>
        /// <param name="sql">执行增删改的sql语句</param>
        /// <returns>返回数据库中受影响的行数</returns>
        public int NoQuery(string sql)
        {
            this.OpenConnection();
            command = new SqlCommand(sql,comm);
            int result = command.ExecuteNonQuery();
            this.CloseConnection();
            return result;
        }

        #endregion

        #region 查询单个值[聚合函数]
        /// <summary>
        /// 用户执行数据查询单个值[聚合函数]
        /// </summary>
        /// <param name="sql">执行查询的sql语句</param>
        /// <returns>返回单个值</returns>
        public int Aggre(string sql)
        {
            this.OpenConnection();
            command = new SqlCommand(sql, comm);
            int result = (int)command.ExecuteScalar();
            this.CloseConnection();
            return result;
        }

        #endregion

        #region 断开式查询
        /// <summary>
        /// 断开式查询
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public DataSet GetList(string sql)
        {
            ds = new DataSet();
            adapter = new SqlDataAdapter(sql,comm);
            adapter.Fill(ds,"Info");
            return ds;
        }

        #endregion

    }
}

完整DBHelper 数据库操作基类