_priority=_priority==0？0：_priority；
var qry=from c in ctxt.Tasks where 1=1 && c.priority==_priority select c;

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var p= from c in ctxt.Tasks  select c;
if (!string.IsNullOrEmpty(ddlpriority.SelectedValue))  
   p= p.Where(s => s._priority == ddlpriority.SelectedValue);

IQueryable<T> query = from c in ctxt.Tasks 
where (c.priority == null ||  c.priority ==_priority )  
select c;


------解决方案--------------------

C# code

IQueryable<Tasks> v = from t in Tasks
        select t;
if (!string.IsNullOrEmpty(ddlpriority.SelectedValue)) 
{
   v.Where (p=>p.priority == ddlpriority.SelectedValue);
}

------解决方案--------------------
C# code
IQueryable<Tasks> v = from t in Tasks
       select t;
if (!string.IsNullOrEmpty(ddlpriority.SelectedValue))  
{
  v.Where (p=>p.priority == ddlpriority.SelectedValue);
}



------解决方案--------------------
d

------解决方案--------------------
提供表结构
测试信息
极其想要的结果
我帮你用sql写

------解决方案--------------------
也开始接触linq了，有很多都不会转

------解决方案--------------------
探讨

var p= from c in ctxt.Tasks  select c;
if (!string.IsNullOrEmpty(ddlpriority.SelectedValue))
    p= p.Where(s => s._priority == ddlpriority.SelectedValue);

IQueryable <T> query = from c in ctxt.Tasks 
where (c.priority == null ||  c.priority ==_priority )
select c;