Recent Quizzes from the PL/SQL Challenge

In the month of September (to date), over 1260 Oracle technologists submitted 14,360 answers to quizzes, and explored the library of past quizzes. Here is a selection of quizzes from this month:

Oracle PL/SQL Quizzes

12 September 2011: You can trap an exception by name or you can trap it with WHEN OTHERS. If you know which exceptions might be raised, it is generally better to include a handler for that specific exception, usually so that you can also log more specific information about what might have caused the error.
610 Players ** Avg. Correct: 88% ** Avg. Time: 200 seconds ** Rating: 4 stars

13 September 2011: When an exception is raised in the declaration section (such as by assigning a too-long string as the default value for a variable), the exception propagates out unhandled from that block - even if there is an exception section and OTHERS clause.
638 Players ** Avg. Correct: 37% ** Avg. Time: 320 seconds ** Rating: 4 stars

14 September 2011: If the body of your result cache function depends on settings that might vary from session to session (such as NLS_DATE_FORMAT and TIME ZONE), make the function result-cached only if you can modify it to handle the variations in settings that might occur.
612 Players ** Avg. Correct: 69% ** Avg. Time: 259 seconds ** Rating: 4 stars

15 September 2011: When comparing values that may be NULL, pay close attention to handling all possible cases, to ensure that the correct Boolean value is returned.
604 Players ** Avg. Correct: 65% ** Avg. Time: 212 seconds ** Rating: 4 stars

16 September 2011: In case a dynamic SQL statement makes repeated use of a placeholder name, it is necessary to provide a bind value in the USING clause for each occurrence. In the same situation, when executing a dynamic PL/SQL block, only one value should be specified for each placeholder name, even if it is used several times.
576 Players ** Avg. Correct: 64% ** Avg. Time: 220 seconds ** Rating: 4 stars
19 September 2011: When writing complex Boolean expressions with multiples ANDs and ORs, remember that AND takes precedence over OR. Use parentheses to remove any possible ambiguity in your understanding of how the statement will be evaluated.
595 Players ** Avg. Correct: 94% ** Avg. Time: 156 seconds ** Rating: 4 stars

20 September 2011: Use CURRENT OF with FOR UPDATE to avoid writing or repeating unnecessary logic in a WHERE clause for DELETEs and UPDATEs inside your loop.
647 Players ** Avg. Correct: 88% ** Avg. Time: 278 seconds ** Rating: 4 stars
21 September 2011: You cannot define a nested block as an autonomous transaction. If you need that behavior, simply create a nested procedure within the nested block, and then define that procedure as an autonomous transaction.
634 Players ** Avg. Correct: 72% ** Avg. Time: 343 seconds ** Rating: 4 stars

22 September 2011: Make sure that any expressions executed within a loop must be re-evaluated with each iteration of the loop body. If they do not change (they are "loop invariants"), then execute the expression once, assign the outcome to a local variable, and reference that variable inside the loop.
610 Players ** Avg. Correct: 65% ** Avg. Time: 400 seconds ** Rating: 4 stars

23 September 2011: When writing complex numeric expressions involving several different types of operators, make sure that you both understand the precedence by which the operators are applied and that you use parentheses to ensure that the expression is evaluated as desired.
589 Players ** Avg. Correct: 91% ** Avg. Time: 123 seconds ** Rating: 4 stars

SQL Quizzes

Here are the SQL quizzes played in September: 3 September 2011: Use of analytic function COUNT with the RANGE clause to count records with values within defined ranges.
520 Players ** Avg. Correct: 82% ** Avg. Time: 2082 seconds ** Rating: 4 stars

10 September 2011: Partitioned outer join is one of the most useful data densification techniques available since Oracle10g.
526 Players ** Avg. Correct: 61% ** Avg. Time: 4645 seconds ** Rating: 4 stars

17 September 2011: Use of analytic function RATIO_TO_REPORT to show "percent of total" in select statements.
474 Players ** Avg. Correct: 72% ** Avg. Time: 2931 seconds ** Rating: 4 stars

APEX Quizzes

Here are the APEX quizzes played in September:

3 September 2011: This question will teach users how the APEX data dictionary views can be used to find out information about the applications in the workspace.
223 Players ** Avg. Correct: 59% ** Avg. Time: 925 seconds ** Rating: 4 stars

10 September 2011: Shows different methods of customising error messages inside APEX that will save time repeating code.
199 Players ** Avg. Correct: 56% ** Avg. Time: 208 seconds ** Rating: 4 stars

17 September 2011: Learm how to correctly send emails using the apex_mail.send procedure.
206 Players ** Avg. Correct: 66% ** Avg. Time: 2206 seconds ** Rating: 4 stars