Monday, April 10, 2006

1. Create a join based on the cost of the event between the DJs on Demand tables D_EVENTS and D_PACKAGES. Show the name of the event and the code for each event.

---- select,dp.code
from d_events de, d_packages dp
where de.cost between dp.low_range and dp.high_range;

2. Using the Oracle database, create a query that returns the employee last name, salary, and job-grade level based on the salary. Select the salary between the lowest and highest salaries.

----select e.last_name,e.salary, jg.grade_level
from employees e, job_grades jg
where salary between lowest_sal and highest_sal

3. What condition requires creation of a nonequijoin?

---- Since there is no exact match between the two columns in each table.

4. Rewrite the following nonequijoin statement using the logical condition operators (AND, OR, NOT):
WHERE a.ranking BETWEEN g.lowest_rank AND g.highest_rank

----ranking >= g.lowest_rank and <= g.highest_rank

5. How do you know when to use a table alias and when not to use a table alias?

----the column is so long, and the column has to be used many times

6. What is the purpose of the WHERE clause in a join?

----provide the condition

7. What kind of join would you use if you wanted to find data between a range of numbers?


8. What kind of join would you use if you wanted to join two tables on any rows that have the same name and the same data type.