EF简单的增删改查

「爱情、让人受尽委屈。」 2023-06-08 10:57 33阅读 0赞 
  1. JSDEntities edm = new JSDEntities();
  5.             //select
  7.             var temp = from p in edm.accounts_top_up
  9.                        where p.ID == 18410
  11.                        select p;
  13.             accounts_top_up atu = temp.Single();
  17.             //update
  19.             accounts_top_up at = new accounts_top_up() { USER_ID = 18412, ID = 18412 };
  21.             DbEntityEntry<accounts_top_up> entry = edm.Entry<accounts_top_up>(at);
  23.             entry.State = System.Data.EntityState.Unchanged;  
  25.             entry.Property("USER_ID").IsModified = true;
  27.             edm.SaveChanges();
  31.             //add
  33.             accounts_top_up a = new accounts_top_up() { USER_ID = 18412, ID = 18412 };
  35.             edm.accounts_top_up.Add(a);
  37.             edm.SaveChanges();
  41.             //delete
  43.             edm.Entry<accounts_top_up>(new accounts_top_up() {  ID = 18411}).State = EntityState.Deleted
  45.             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();

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