How can I write this query in linq to sql?

Question

I'm new in linq and want to write this query:

var query = from p in behzad.rptost
            where p.date.substring(0, 4) == "1395"
            -->in this calc sum=p.price_moavaq+price_year
            select p;

How can I write that query?

Answer 1

From what I assume you are trying to sum up the price_moavaq field per year. Furthermore, by the use of the substring I guess your date field isn't of DateTime type but just a string .

So you need to use a groupby :

var query = from p in behzad.rptost
            group p by p.date.substring(0, 4) into grouping
            select new { Year = p.Key, Sum = p.Sum(x => x.price_moavaq);

In the case that your date field is of DateTime type then just use .Year :

var query = from p in behzad.rptost
            group p by p.date.Year into grouping
            select new { Year = p.Key, Sum = p.Sum(x => x.price_moavaq);