EF框架实增删改查

数据库链接配置：

<connectionStrings>
<add name="XxzxWorkEntities" connectionString="metadata=res://*/fenlei.csdl|res://*/fenlei.ssdl|res://*/fenlei.msl;provider=System.Data.SqlClient;provider connection string="data source=localhost;initial catalog=XxzxWork;user id=sa;password=123!@#;MultipleActiveResultSets=True;App=EntityFramework"" providerName="System.Data.EntityClient" />
</connectionStrings>

　　增、删、改、查实例

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

namespace EFtest
{
    class Program
    {
        static void Main(string[] args)
        {
            var db = new XxzxWorkEntities();
            //删除
            var  fenleiDel = db.CategoryMaintenance.First(p => p.ID == "666");
            db.CategoryMaintenance.Remove(fenleiDel);
            db.SaveChanges();

            //新增
            var newfenlei = new CategoryMaintenance();
            newfenlei.ID = "666";
            newfenlei.Name = "666";
            newfenlei.ParentID = "top";
            newfenlei.ContentType = "内容";
            newfenlei.IsEffective = "是";
            db.CategoryMaintenance.Add(newfenlei);
            db.SaveChanges();

            //修改
            var fenleiObj = db.CategoryMaintenance.First(a => a.ID == "666");
            fenleiObj.Name = "666被修改22";
            db.CategoryMaintenance.Attach(fenleiObj);
            db.Entry(fenleiObj).State = EntityState.Modified;
            db.SaveChanges();

            //查询
            var Item = db.CategoryMaintenance.Where(a =>a.ParentID=="top" && a.IsEffective=="是").OrderBy(a => a.ID).ToList();
            foreach (var fenlei in Item)
            {
                if (fenlei.Name.ToString()=="测试")
                {
                    //跨表查询
                    var subItem = db.XxzxMainMsg.Where(b => b.BigFl == "主栏目"&&b.IsDeleted == null && b.SmallFl == fenlei.Name.ToString());
                    Console.Write(fenlei.Name + "\n");
                    foreach (var subneirong in subItem)
                    {
                        Console.Write(subneirong.STitle + "\n");
                    }
                }
            }
            Console.ReadKey();
        }
    }
}