Friday, 14 June 2013

LINQ Hour 5 -1 Aggregate function in LINQ

Written By:-Isha Malhotra 
Aggregate function using LINQ

We use many aggregate functions like sum, count, average, min, and max. In LINQ we can use this function in the following manner:-


If we want to perform sum aggregate function then we will implement the following queries:-

Sum with array

int[] marks = new int[] { 23, 45, 78, 90, 56, 89, 10, 32 };

        //simple sum without condition

        int res = marks.Sum();

        //sum with condition
        int res_with_where = marks.Where(cond => cond > 50).Sum();


        Response.Write("Sum without condition= " + res + "<br/>");

        Response.Write("Sum with condition="+ res_with_where+"<br/>");

Output of this code as follows:-

Figure 1

Sum with Generics

List<data> dt = new List<data>()
            new data{roll_no=1, student="isha", per=100},
            new data{roll_no=2, student="neha", per=89},
            new data{roll_no=3, student="rahul", per=34}

        int per_sum = dt.Sum(x => x.per);

        int per_sum_with_conditon = dt.Where(stu => stu.student.EndsWith("ha")).Sum(x => x.per);

        Response.Write("Sum without condition= " + per_sum + "<br/>");

        Response.Write("Sum with condition=" + per_sum_with_conditon + "<br/>");

Output of this code as follows:-

Figure 2

Sum with database:-

DataContext dc = new DataContext("Data Source=.;Initial Catalog=TechAltum;Integrated Security=True");
        //sum without condition
        int sum_without_cond = dc.GetTable<Class1>().Sum(prod_sum => prod_sum.no_of_prod);

        //sum with conditon

        int sum_with_cond = dc.GetTable<Class1>().Where(cond => cond.prod_year == 2001).Sum(prod_sum => prod_sum.no_of_prod);

        Response.Write("Sum without conditon=" + sum_without_cond + "<br/>");
        Response.Write("Sum with conditon=" + sum_with_cond + "<br/>");

Output of this code as follows:-

Figure 3

Similarly we can perform max, min, average and count using LINQ.

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