Last week, 841 Oracle technologists submitted 2,548 answers to quizzes. Here are the PL/SQL quizzes played that week:
22 August 2011: When you use the FOR UPDATE clause in your query, Oracle will lock all rows identified by the SELECT statement. When you specify columns with FOR UPDATE OF, locks will be placed only on rows in tables whose columns are in the list.
620 Players ♦ Avg. Correct: 79% ♦ Avg. Time: 325 seconds ♦ Rating: 4 stars
23 August 2011: When writing a CASE statement, you should always include an ELSE clause - unless you are absolutely sure that one of the WHEN clauses will always evaluate to TRUE. That's a big assumption to make.
644 Players ♦ Avg. Correct: 54% ♦ Avg. Time: 110 seconds ♦ Rating: 4 stars
24 August 2011: When you initialize an object type instance, you must supply an expression for each attribute. When you initialize a nested table or varray, you do not need to supply any expressions (elements) for the array.
670 Players ♦ Avg. Correct: 75% ♦ Avg. Time: 335 seconds ♦ Rating: 4 stars
25 August 2011: Use TRUNC to remove the specified number of significant digits from a number. Use TRUNC, in particular, when you do not want rounding to be performed on the number.
661 Players ♦ Avg. Correct: 87% ♦ Avg. Time: 271 seconds ♦ Rating: 4 stars
26 August 2011: The value of the LAST_DDL_TIME column of the ALL_OBJECTS and USER_OBJECTS data dictionary views is updated whenever the object is changed (for example, when code is changed and then compiled). But this column value is not changed if you replace a program and the code has not been modified.
627 Players ♦ Avg. Correct: 24% ♦ Avg. Time: 425 seconds ♦ Rating: 4 stars
The PL/SQL Challenge (www.plsqlchallenge.com) offers a daily quiz on the PL/SQL language, through which thousands of Oracle technologists demonstrate and deepen their knowledge of PL/SQL. This blog contains posts by the PL/SQL Challenge founder, Steven Feuerstein, as well as comments from players.
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