Brian Dunning wrote:
How do I query "How many calories did Brian eat on 2009-09-04"?
Table:People
+-----------+-------+
+ Person_ID + Name |
+-----------+-------+
| 5 | Brian |
+-----------+-------+
Table:Meals
+---------+-----------+-----------+------------+
| Meal_ID | Person_ID | Meal_Name | Date |
+---------+-----------+-----------+------------+
| 3 | 5 | Breakfast | 2009-09-04 |
| 4 | 5 | Lunch | 2009-09-04 |
+---------+-----------+-----------+------------+
Table:Meal_Items
+-------------+---------+-----------+----------+
| MealItem_ID | Meal_ID | Item_Name | Calories |
+-------------+---------+-----------+----------+
| 16 | 3 | Banana | 100 |
| 17 | 3 | Milk | 150 |
| 18 | 4 | Cookie | 200 |
+-------------+---------+-----------+----------+
SELECT sum(calories) from People
INNER JOIN Meals ON People.Name=Meals.Name
INNER JOIN Meal_Items on Meals.Meal_ID=Meal_Items.Meal_ID
WHERE Name='Brian' AND Date='2009-09-04';
--
Gerald L. Clark
Sr. V.P. Development
Supplier Systems Corporation
Unix since 1982
Linux since 1992
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