LINQ to SQL advice - why won't it work?

Question

I'm trying to write a LINQ query that that simply gets the count of rows where a variable ('id') is equal to the JOB_GROUP statement. Problem is, Visual Studio is returning an error on the ; at the end, saying 'Only assignment calls.....may be used as a statement'. Is there anything obvious wrong with my query?

var noofrows = from s in dc.QRTZ_JOB_DETAILs 
                where id == s.JOB_GROUP
               select s.JOB_NAME.Count();

Answer 1

You need to wrap the linq query around parentheses before calling the Count() method.

var noofrows = (from s in dc.QRTZ_JOB_DETAILs 
                where id == s.JOB_GROUP 
                select s.JOB_NAME).Count();

Answer 2

更轻巧，更易读：

 var count = dc.QRTZ_JOB_DETAILs.Count(x=>id == x.JOB_GROUP );

Answer 3

或者，您可以简单地编写：

var noofrows = dc.QRTZ_JOB_DETAILs.Count(s => id == s.JOB_GROUP);