Difference between revisions of "Introduction to Databases with Stanford University : Relational Algebra Exercises"
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− | + | * Introduction to Databases by Standford University http://db-class.org | |
+ | * Additional materials: http://openclassroom.stanford.edu/MainFolder/CoursePage.php?course=IntroToDatabases | ||
1. Find all pizzas eaten by at least one female over the age of 20. | 1. Find all pizzas eaten by at least one female over the age of 20. | ||
Line 7: | Line 8: | ||
\select_{gender='female' and age > 20} Person | \select_{gender='female' and age > 20} Person | ||
\join Eats) | \join Eats) | ||
+ | </pre> | ||
+ | |||
+ | 2. Find the names of all females who eat at least one pizza served by Straw Hat. (Note: The pizza need not be eaten at Straw Hat.) | ||
+ | |||
+ | <pre> | ||
+ | \project_{name} ( | ||
+ | \select_{gender='female'} ( | ||
+ | ( \select_{pizzeria='Straw Hat'} Serves | ||
+ | \join Eats | ||
+ | ) \join Person | ||
+ | ) | ||
+ | ) | ||
+ | </pre> | ||
+ | |||
+ | 3. Find all pizzerias that serve at least one pizza for less than $10 that either Amy or Fay (or both) eat. | ||
+ | |||
+ | <pre> | ||
+ | \project_{pizzeria} ( | ||
+ | \select_{name='Amy' or name='Fay'} ( | ||
+ | \select_{price < 10} Serves | ||
+ | \join Eats | ||
+ | ) | ||
+ | ) | ||
</pre> | </pre> |
Revision as of 17:49, 16 November 2011
- Introduction to Databases by Standford University http://db-class.org
- Additional materials: http://openclassroom.stanford.edu/MainFolder/CoursePage.php?course=IntroToDatabases
1. Find all pizzas eaten by at least one female over the age of 20.
\project_{pizza} ( \select_{gender='female' and age > 20} Person \join Eats)
2. Find the names of all females who eat at least one pizza served by Straw Hat. (Note: The pizza need not be eaten at Straw Hat.)
\project_{name} ( \select_{gender='female'} ( ( \select_{pizzeria='Straw Hat'} Serves \join Eats ) \join Person ) )
3. Find all pizzerias that serve at least one pizza for less than $10 that either Amy or Fay (or both) eat.
\project_{pizzeria} ( \select_{name='Amy' or name='Fay'} ( \select_{price < 10} Serves \join Eats ) )