EF简单的增删改查

「爱情、让人受尽委屈。」 2023-06-08 10:57 2阅读 0赞

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<accounts_top_up> entry = edm.Entry<accounts_top_up>(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<accounts_top_up>(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();