.Net Entity SQL返回相关信息

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Objects;
using System.Collections.Specialized;

namespace TestEsql
{
    class EsqlOper
    {
        //返回基本数据
        public List<BackLog> GetData1()
        {
            List<BackLog> list = new List<BackLog>();
            using (OMCAUDITEntities db = new OMCAUDITEntities())
            {
                db.BackLog.MergeOption = MergeOption.NoTracking;
                list = db.BackLog.ToList();
            }
            return list;
        }

        //返回一个字段
        public string GetOneCol()
        {
            using (OMCAUDITEntities db = new OMCAUDITEntities())
            {
                return db.BackLog.FirstOrDefault(d => d.UserName == "Admin").UserName;
            }
        }

        //返回两个字段，其中一个为主键
        public Dictionary<DateTime, String> GetTwoCol()
        {
            using (OMCAUDITEntities db = new OMCAUDITEntities())
            {
                Dictionary<DateTime, String> dic = db.BackLog.ToDictionary(new Func<BackLog, DateTime>(c => c.LogTime), new Func<BackLog, String>(c => c.UserName));
                //也可以直接像下面这样写
                Dictionary<DateTime, String> dic2 = db.BackLog.ToDictionary(c => c.LogTime, c => c.UserName);
                return dic;
            }
        }

        //返回多个字段
        public object GetManyCol()
        {
            using (OMCAUDITEntities db = new OMCAUDITEntities())
            {
                object query = db.BackLog.Select(c => new { c.LogTime, c.UserName, c.LogType, c.LoginIp }).ToList();
                return query;
            }
        }

        public bool DeleteMany()
        {
            NameValueCollection conditionvalue = new NameValueCollection();
            conditionvalue["Name_like"] = "Winson";
            OMCAUDITEntities db = new OMCAUDITEntities();
            BackLog blog = new BackLog();
           
            db.DeleteObject(conditionvalue);
            if(db.SaveChanges()>0)
                return true;
            else
                return false;
        }
        public int DeleteManyCol()
        {
            using (OMCAUDITEntities db = new OMCAUDITEntities())
            {
                Table_1 tab = db.Table_1.FirstOrDefault(d => d.ID == 2);
                if (tab == null)
                    return 0;
                db.DeleteObject(tab);
                if (db.SaveChanges() > 0)
                {
                    List<Table_1> list = db.Table_1.Where(d => d.ID > 200).ToList();
                    foreach (Table_1 st in list)
                    {
                        db.DeleteObject(st);
                    }
                    return db.SaveChanges();
                }
                else
                {
                    return 0;
                }
               
            }
        }
    }
}