In my database class, students write solutions as group exercises against the Oracle 11g XE database and then they port the solution individually to the MySQL 5.5 database. One of the students copied over a query like the one below to MySQL (a query used to track the expected number of row returns) and got an error they didn’t understand:
The 20th June quiz tested your knowledge of how to remove "gaps" from a sparse array (make it dense). Daniel Kennedy posted an objection to the scoring, saying that if you use a NULL value for the index value in the collection, then none of the choices are correct.
Somebody wanted to understand why you can backquote a single wildcard operator (that’s the underscore
_ character) in MySQL, but can’t in Oracle. The answer is you can in Oracle when you know that you required an additional clause.
While I prefer using regular expression resolution, the
LIKE operator is convenient. Here’s an example of backquoting an underscore in MySQL, where it looks for any string with an underscore anywhere in the string:
Hope you all are liking the book and my wish that it reaches my readers. I am satisfied with the good response of the readers. The fact that the book features into Oracle magazine (July-August 2012) issue and Oracle ACE newsletter has already overwhelmed me with joy and excitement.
Dear PL/SQL Challenge Players,
I made a very big mistake today, and the result is that many of you could not play Monday's quiz.
I switched to maintenance mode at 15:00 to fix a bug, but then neglected to return to normal mode of play.
Then, seeing as I am in Taos, NM, I left the world of computers behind for Bandelier National Monument, an amazing place....but as a result, I did not notice that so many of you were notifying me of a problem with the site.
My deepest apologies. We will have to void the results for Monday's quiz.