Questions from Database Systems

Q: Explain why the two following commands produce different results. SELECT

Explain why the two following commands produce different results. SELECT DISTINCT COUNT (V_CODE) FROM PRODUCT; SELECT COUNT (DISTINCT V_CODE) FROM PRODUCT;

Q: What is the difference between the COUNT aggregate function and the SUM

What is the difference between the COUNT aggregate function and the SUM aggregate function?

Q: Write an example of a database request.

Write an example of a database request.

Q: Modify the query used in Problem 29 to produce the summary shown

Modify the query used in Problem 29 to produce the summary shown in Figure P7.30. FIGURE P7.30 Customer Purchase Summary

Q: Explain why it would be preferable to use a DATE data type

Explain why it would be preferable to use a DATE data type to store date data instead of a character data type.

Q: What is a recursive join?

What is a recursive join?

Q: Given the employee information in Question 11, what is the query

Given the employee information in Question 11, what is the query output for the INTERSECT query? (List the query output.) Details from Question 11: Suppose that you have two tables, EMPLOYEE and EMPL...

Q: Given the employee information in Question 11, what is the query

Given the employee information in Question 11, what is the query output for the MINUS query? (List the query output.) Details from Question 11: Suppose that you have two tables, EMPLOYEE and EMPLOYEE_...

Q: Why does the order of the operands (tables) matter in

Why does the order of the operands (tables) matter in a MINUS query but not in a UNION query?

Q: What MS Access/SQL Server function should you use to calculate

What MS Access/SQL Server function should you use to calculate the number of days between the current date and January 25, 1999?