Grouping my data in ASP.NET - asp.net

Question

I hava this table in data base
http://i.stack.imgur.com/r7ECj.jpg
I want to group data in this form
------------ Group 1 -------------
1.FoodGroupName : Milk
a.FoodSubGroup: Milk(type1)
1.food 1
2.food 2
3.food 3
4.food 4
b.FoodSubGroup: Milk(type2)
1.food 1
2.food 2
3.food 3
4.food 4
c.FoodSubGroup: Milk(type3)
1.food 1
2.food 2
3.food 3
4.food 4
--------- Group 2 ------------
2.FoodGroupName : Meat
a.FoodSubGroup: Meat(type1)
1.food 1
2.food 2
3.food 3
4.food 4
b.FoodSubGroup: Meat(type2)
1.food 1
2.food 2
3.food 3
4.food 4
c.FoodSubGroup: Meat(type3)
1.food 1
2.food 2
3.food 3
4.food 4

Answer 1

You could use a query like this:
SELECT fg.FoodGroupName, fsg.FoodSubGroupName, f.FoodName
FROM FoodGroups fg
INNER JOIN FoodSubGroups fsg
ON fg.FoodGroupId = fsg.FoodGroupId
INNER JOIN Foods f
ON fsg.FoodSubGroupId = f.FoodSubGroupId
ORDER BY fg.FoodGroupName, fsg.FoodSubGroupName, f.FoodName
to retrieve data and then output results as you please...

Answer 2

There is several ways to do that kind of thing :
1) you write a single query that will combines the 3 table (using joins) and return a single dataset (like Marco suggested).
eg :
Group SubGroup Food
--------------------------------
Meat Meat1 Food 1
Meat Meat1 Food 2
Meat Meat1 Food 3
Meat Meat2 Food 1
Milk Milk1 Food 1
Milk Milk2 Food 1
Then by using C# code, you group them.
You can do this using very few lines of code (and efficiently) by using GroupBy() linq lambda expression. Have also a look at ToLookUp() extension.
If you are not familiar with them, check this page :
http://code.msdn.microsoft.com/LINQ-to-DataSets-Grouping-c62703ea
In the end you should get a collection of objects that allows you to do the following:
var groups = ...
foreach(var group in groups)
{
//do something with group
foreach(var subGroup in group.SubGroups)
{
//do something with subGroup
foreach(var food in subGroup.Foods)
{
//do something with food
}
}
}
Then it is very easy to fill a treeview or present data using nested repeaters.
2) you write independent queries that will query each table separately. In the end, you get 3 datasets.
Group
-------
1 Meat
2 Milk
SubGroup
---------
1 1 Meat1
2 1 Meat2
3 2 Milk1
4 2 Milk2
Food
----------
1 1 Food 1
2 1 Food 2
3 1 Food 3
4 2 Food 1
5 3 Food 1
6 4 Food 1
Then you use can Group Join linq operator to group them.
In that case, C# will do the joins for you, not sql.
Check here : http://code.msdn.microsoft.com/LINQ-Join-Operators-dabef4e9/description#groupjoin
In the end you will get same result at 1). Both have advantages / disavantages.