DBHelper

DBHelper:

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

namespace DAL
{
    public class DBhelper
    {
        private static string Constr = "server=.;database=PaiPaiDB;uid=sa;pwd=123";
        private static SqlConnection conn;
        private static SqlDataAdapter da;
        private static SqlCommand cmd;
        private static DBhelper dbhelper;

        public DBhelper()
        {
            conn = new SqlConnection(Constr);
        }

        public static DBhelper Instance()
        {
            if (dbhelper == null)
            {
                dbhelper = new DBhelper();
            }
            return dbhelper;
        }

        void DBOpen()
        {
            if (conn.State == ConnectionState.Closed)
            {
                conn.Open();
            }
        }

        void DBClose()
        {
            if (conn.State == ConnectionState.Open)
            {
                conn.Close();
            }
        }

        public DataTable GetDtatTableBySql(string sql)
        {
            DBOpen();

            DataTable dt = new DataTable();
            da = new SqlDataAdapter(sql, conn);
            try
            {
                da.Fill(dt);
                return dt;
            }
            catch (Exception)
            {

                return null;
            }
            finally
            {
                DBClose();
            }
        }

        public bool ExcuteSql(string sql)
        {

            DBOpen();
            cmd = new SqlCommand(sql, conn);
            try
            {
                cmd.ExecuteNonQuery();
                return true;
            }
            catch (Exception)
            {
                return false;
            }
            finally
            {
                DBClose();
            }
        }

        public bool ExcuteProcedure(string proName, SqlParameter[] paras)
        {
            DBOpen();
            cmd = new SqlCommand(proName, conn);
            cmd.CommandType = CommandType.StoredProcedure;
            for (int i = ; i < paras.Length; i++)
            {
                cmd.Parameters.Add(paras[i]);
            }
            try
            {
                cmd.ExecuteNonQuery();
                return true;
            }
            catch (Exception)
            {
                return false;
            }
            finally
            {
                DBClose();
            }
        }
    }
}

调用方法：

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

namespace DAL
{
    public class GoodsService
    {
        //查询
        public static DataTable GetDtatTableBySql(string sql)
        {

            DataTable dt = DBhelper.Instance().GetDtatTableBySql(sql);
            if (dt != null && dt.Rows.Count > )
            {
                return dt;
            }
            else
            {
                return null;
            }
        }
        //增加 删除  修改
        public static bool ExecuteSql(string sql)
        {
            bool a;
            a = DBhelper.Instance().ExcuteSql(sql);
            return a;
        }

    }
}