EF简单的增删改查

 JSDEntities edm = new JSDEntities();

 

            //select

            var temp = from p in edm.accounts_top_up

                       where p.ID == 18410

                       select p;

            accounts_top_up atu = temp.Single();

 

            //update

            accounts_top_up at = new accounts_top_up() { USER_ID = 18412, ID = 18412 };

            DbEntityEntry entry = edm.Entry(at);

            entry.State = System.Data.EntityState.Unchanged;  

            entry.Property("USER_ID").IsModified = true;

            edm.SaveChanges();

 

            //add

            accounts_top_up a = new accounts_top_up() { USER_ID = 18412, ID = 18412 };

            edm.accounts_top_up.Add(a);

            edm.SaveChanges();

 

            //delete

            edm.Entry(new accounts_top_up() {  ID = 18411}).State = EntityState.Deleted

            edm.SaveChanges();

2:模糊查询
actualContext.PU.Where(a=>a.ErrorReason.Contains("sdfsdf"))使用Contains关键字

3:   var list = from entity in actualContext.PSI   where (string.IsNullOrEmpty(entity.QYPortEN) || entity.QYPortEN == priceinfo.QYPortEN)      select entity;

4:where if

 where ((sortBy == "Buy equipment") ? entity.Type == "Sell" : true) &&  ((sortBy == "Sell equipment") ? entity.Type == "Buy" : true)
分组查询：

entities db=new entities();

var rslt=from u in tb group u by u.name into g

select new { subject=g.key,average=g.average(u=>u.score),sum=g.sum(a=>a.score)}

var list=rslt.tolist();

分组方法二：

var list=ote.score.GroupBy(a=>a.SubName).Select(a=>new{ subject=a.key,average=a.average(b=>b.score) }).tolist();