# Assignment 7: Queries and Optimization Due Week 8 and worth 50 pointsYour supervisors and customers are very impressed with the database you have put together. However, there is still that questioning...

Assignment 7: Queries and OptimizationDue Week 8 and worth 50 pointsYour supervisors and customers are very impressed with the database you have put together. However, there is still that questioning executive that wants validation the database is useful; after all, he is saying that we have put a lot of data in, but does not see information out. To this end, you will be designing reports / queries that will be of use to the restaurant executives and other managers of the company.Write a 2-3 page paper in which you:
• Describe a minimum of three (3) heuristics to optimize Queries.
• Provide the SQL code (and screen shots) based on the following criteria:
• You must deliver five (5) queries in total for this assignment.
• One of your five queries must select from three (3) different tables.
• Four of your queries must select from two (2) tables.
• Include comments on how you are using the optimization rules you described and discussed earlier.
• Use at least three (3) quality resources in this assignment. Note: Wikipedia and similar Websites do not qualify as quality resources.
• Be typed, double spaced, using Times New Roman font (size 12), with one-inch margins on all sides; citations and references must follow APA or school-specific format. Check with your professor for any additional instructions.
• Answered Same DayDec 20, 2021

## Solution

David answered on Dec 20 2021
Query optimization
A query has many possible strategies for execution. The process of selecting the suitable strategy for query processing is known as query optimization. Every query is transformed into equivalent relational alge
a which is then sent for optimization.
Query optimizers are defined as a set of equivalence rules of relational alge
a. They are formed in order to improve the performance of query processing. Though they are not successful in all the cases. There are various techniques available for query optimization.
The paper discusses about the application of heuristic rules in query optimization. The rules are based on following equivalence rules:
1. Deconstruct the conjunctive selection into a sequence of individual selection (8 Query Optimization).
σp1∧p2 (E) ≡ σp1 (σp2 (E))
2. Selection based operations are commutative.
σp1(σp2(E)) ≡ σp2(σp1(E))
3. When the equivalent relational alge
a has more than one projection, only the last projection is
selected (i.e. required) and rest are omitted (8 Query Optimization).
πL1(πL2(· · · πLn(E)· · ·)) ≡ πL1(E)
4. Selections can be formed by combining products and joins (8...
SOLUTION.PDF