The biggest problem with learning on an "as-needed" basis: You only learn what's needed to accomplish your immediate goals. An inefficient, injectable query wil

The biggest problem with learning on an "as-needed" basis: You only learn what's needed to accomplish your immediate goals. An inefficient, injectable query will certainly get data showing up on your web page. Most people are not going to "learn databases" over the weekend. A boss or company that has employees capable of this type of independent learning and routinely expects it will soon lose the former. That costs more than 2 cents.