asp.net multiple sqlcommands in one GridView - asp.net

Question

I have problem to show multiple sql command in one GridView. Maybe I don't need two sqlcommands to show from two tables but I don't know how to do.
The first command is to get all employees that have vacation between two dates.
The second command I am using it to retrieve dates by ID. But I don't know how to Bind them both to one GridView to show as attached image. Thank you in advance.
What I get Now is
Albert 2016-03-16
Albert 2016-03-17
Albert 2016-03-18
Johanna 2016-03-17
Johanna 2016-03-18
Eric 2016-03-18
Instead of
Albert 2016-03-16, 2016-03-17, 2016-03-18
Johanna 2016-03-17, 2016-03-18
Eric 2016-03-18
I think I have to loop between two While statment and maybe with one sqlcommand?
My code is:
using (SqlConnection con = new SqlConnection(connection))
{
con.Open();
SqlCommand cmd = new SqlCommand(" SELECT distinct E.EmployeeId, E.FirstName
FROM Employee E INNER JOIN Vacation V ON E.EmployeeId = V.EmployeeId " +
" WHERE ((V.Dates >= #Start AND V.Dates <= #End) ) ", con);
cmd.Parameters.AddWithValue("#Start", (Calendar1.SelectedDates[0]).Date.ToShortDateString());
cmd.Parameters.AddWithValue("#End", (Calendar1.SelectedDates[Calendar1.SelectedDates.Count - 1]).Date.ToShortDateString());
using (SqlDataReader dr = cmd.ExecuteReader())
{
while (dr.Read())
{
Response.Write((dr[1]).ToString() + " "); // Cheack if retrivs Employeename
// Now By Id I want to get all dates belong to specifik employee
SqlCommand cmd2 = new SqlCommand(" SELECT V.Dates FROM Vacation V " +
" WHERE ((V.Dates >= #Start AND V.Dates <= #End) ) ", con);
cmd2.Parameters.AddWithValue("#Start", (Calendar1.SelectedDates[0]).Date.ToShortDateString());
cmd2.Parameters.AddWithValue("#End", (Calendar1.SelectedDates[Calendar1.SelectedDates.Count - 1]).Date.ToShortDateString());
cmd2.Parameters.AddWithValue("#EmployeeId", Convert.ToInt32(dr[0]));
using (SqlDataReader dr2 = cmd2.ExecuteReader())
{
while (dr2.Read())
{
//Response.Write(Convert.ToDateTime(dr2[0]));
GridView7.DataSource = cmd2.ExecuteReader();
GridView7.DataBind();
}
}
Response.Write("<br/>");
}
}
con.close();
}
GridView7.DataSource = cmd.ExecuteReader();
GridView7.DataBind();

Answer 1

The FOR XML PATH syntax allows your query to group several values in a single one:
SELECT
E.EmployeeId,
E.FirstName,
REPLACE(STUFF((
SELECT
COALESCE('¶' + V.Dates, '')
FROM
Vacation V
WHERE
V.EmployeeId = E.EmployeeId AND V.Dates >= #Start AND V.Dates <= #End
FOR XML PATH('')), 1, 1, ''), '¶', ', ') AS VacationDates
FROM
Employee E
You can replace the ', ' separator by something else if you want.
Note: Sorry for the multipe edits. I am just not sure how you connect the employees, vacations and dates. This piece of code basically shows the idea for the FOR XML PATH syntax.