sql query with multiple headers and multiple counts

Question

I have a table with client task details (attached picture). I want result like number of tasks received for a particular month for each client, no. of tasks completed within 5days from the start date and its compliance. could someone help with a SQL query

client | No.of tasks of a month | No.of tasks completed on time | % of compliance
A      | 5                      | 4                             | 75%

Answer 1

About your last comment, this is a minimal, not-production-ready, idea:

suppose you have a combobox for months and year

cbYear.DataSource = new int[] { 2017, 2018, 2019 };
cbMonth.DataSource = new string[] { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Ago", "Sep", "Oct", "Nov", "Dec" };

and a datagridview dgv, you can do something like this (in a button)

        SqlConnection con = new SqlConnection("Data Source=(LocalDb)\\MSSQLLocalDB;Initial Catalog=test;Integrated Security=SSPI");
        con.Open();
        SqlCommand cmd = con.CreateCommand();
        cmd.CommandText = @"
select 
    x.Client
,   x.MonthTasks
,   x.CompletedOnTime
,   Compliance = x.CompletedOnTime * 100 / x.MonthTasks
from (
    select 
        t.Client
   ,    MonthTasks = Count(1)
   ,    CompletedOnTime = SUM(CASE WHEN DATEDIFF(day, t.TaskStart, t.TaskEnd)<=5 THEN 1 ELSE 0 END)
   from tasks as t
   where
        year(t.TaskStart) = @year
   and month(t.TaskStart) = @month
   group by t.Client
) as x
order by x.Client
        ";

        cmd.Parameters.AddWithValue("@year", cbYear.SelectedItem);
        cmd.Parameters.AddWithValue("@month", cbMonth.SelectedIndex +1);

        var dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
        var dt = new DataTable();
        dt.Load(dr);

        dgv.AutoGenerateColumns = true;
        dgv.DataSource = dt;
        dgv.Refresh();

I repeat you have to catch any errors, maybe transform the query in a stored procedure, but this can be a starting point.