EntityFramework使用详细

//EF增删改查

//查询

Var db=new DbEntities();

Var dt=db.UserInfo.where(i=>ture).ToList();

 

 

//查询带条件的数据

Var bt =db.UserInfo.Where(i=>i.UserInfo==”22”).ToList();

 

 

//多条件查询，&&且  ||或

Var dt=db.UserInfo.Where(i=>i.UserNo==”00”&&i.UserPwd==”11”).ToList();

 

//查询部分字段

Var.list=db.userinfo.where(i=>true).select(i=>new {uerno=i.userno})

 

//模糊查询

Var dt=dt.userInfo.Where(i=>UserNo.contiains(2)).ToList  //%2%

Vat dt=dt.userinfo.where(i=>userno.startswith(“2”)).tolist  //2%

Var dt=dt.userinfo.where(i=>userinfo.endswith(“2”)).tolist   //%2

 

 

//判断数据是否存在

If（dt.Count>0）

{

 

}

 

//分页 1-10  ，11-20  信息数量（页数-1）*每页条数+1

Var dt=db.userInfo.where(i=>ture).skip((2-1)*10).tolist();

Var dt=db.userinfo.where(i=>ture).skip((2-1)*10).tolist();

 

//EF多表关联

Var dt=new db.BookInfo.join(db.book, a=>bookno,b=>bookno,(a,b)=>{a.bookno,b.bookno}).tolist

 

 

//方式二

Var dt =（from

 A in db.bookinfo

  Join

B  in db.booktype on a.booktype equals b.bookType

Join

C in db.publisherinfo on a.publisherno  equals c.publisherno

Where b.bookType==”计算机”

Select new {a.bookno,b,booktype,c.publishername}

）.Tolist();

 

 

//EF执行查询

Db.Database.sqlquery<system>(“selecet*from system”).tolist();

Da.DataexrcuteSqlcommand(“delete from sys009 where user_no={0}”,”sfs”)

update BookInfo set BookName=@BookName where BookNo ='1-001'"  new SqlParameter{ ParameterName="BookName",Value="3"}