Oracle PL/SQL Programming: A Developer's Workbook

Intermediate

Q:
3-10.	You can rewrite this block of code as follows: DECLARE total_sales NUMBER := sales_for_year (company_id=>1056, yearnum=>1998); no_revenue BOOLEAN; BEGIN no_revenue := total_sales <= 0; END; You do not need an IF statement in situations where you assign the value to a Boolean variable. Instead, you can assign the expression that would have appeared in the IF statement, directly to the Boolean. Note that if total_sales is set to NULL, no_revenue is set to NULL in both cases.
Q:
3-11.	In this case, you can’t quite obtain the same behavior by replacing the IF statement with a direct assignment. You might consider the following statement: no_revenue := total_sales <= 0; But you run into trouble if total_sales is NULL. The original code would have set no_revenue to FALSE if total_sales was NULL, since it would cause the ELSE clause to execute. If you replace it with a single line assignment, no_revenue is set to NULL instead of FALSE.
Q:
3-12.	The queue_order_for_addtl_parts procedure is never executed, regardless of the values for order_date, order_total, and min_order_total. For this procedure to run, order_date must be less than or equal to SYSDATE. If this is the case, the second condition would also be TRUE, and then fill_order is run for “LOW PRIORITY”. When working with IF-ELSIF statements, it is extremely important that you make sure the Boolean expressions are mutually exclusive.
Q:
3-13.	There is no difference logically between these two statements. The only difference ...