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Select Query with Counts Help

Posted on 2015-02-16
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Last Modified: 2015-02-16
I have 3 tables. They are actually different but I will make up 3 simple tables to show my problem:

Table 1:
FoodType
FoodTypeId
FoodTypeName

1 Fruit
2 Vegetables
3 Meat

Table 2:
Food
FoodId
FoodName
FoodTypeId

1 Apples, 1
2 Pears, 1
3 Potatoes, 2


Table 3:
Eat
EatId
FoodId

I want to select a count of the food types:
There should be 3 from the FoodType table.
I want to return how many FoodTypeIds are in the Eat table by count. The Eat table doesn't contain a FoodtypeId, but does contain the FoodId which has the FoodtypeId.
In my example, the results I need to return are these (but I will actually return the FoodTypeId, not the FoodName):

Fruit = 2
Vegetables = 1
Meat = 0

Any ideas?

I tried this but it is a dismal failure:
select count(food.footypeid) as typecount, 
food.footypeid
from food
left outer join Eat on food.foodId = Eat.foodId
group by food.foodTypeid
order by count(food.foodTypeid) 

Open in new window


thanks!
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Question by:Starr Duskk
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5 Comments
 
LVL 25

Accepted Solution

by:
chaau earned 2000 total points
ID: 40613257
You need to make sure that the FoodType appears regardless whether it exists in the eat table or not. Therefore it needs to be the first table in the select query and other tables need to be left joined with it:
select ft.footypeid,
ft.FoodTypeName,
coalesce(count(Eat.foodId), 0) as typecount
from FoodType ft 
left outer join food f ON ft.footypeid = f.footypeid
left outer join Eat on f.foodId = Eat.foodId
group by ft.footypeid,
ft.FoodTypeName,
order by coalesce(count(Eat.foodId), 0) desc 

Open in new window

0
 
LVL 49

Expert Comment

by:PortletPaul
ID: 40613275
if Food.FoodTypeId is always present (i.e. not null) then you could use an inner join at line 5 above

no points pl.
0
 
LVL 2

Author Comment

by:Starr Duskk
ID: 40613278
Perfect perfect perfect!!! thanks so much!
0
 
LVL 2

Author Closing Comment

by:Starr Duskk
ID: 40613279
thank you!  (food type is not always present, so that's why I needed it to return a 0 for meat).

PERFECT!

:)
0
 
LVL 2

Author Comment

by:Starr Duskk
ID: 40613292
oh oh, yes, PortletPaul, yes, the Inner Join is good. Then I won't get ones in FoodType that are NOT In Food. They must be in Food. thanks!
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