Sometimes, an observation or question about these pragmata is not merely boilerplate nor blind kowtowing to conventional wisdom.

I agree that the example code is clearly untested and buggy (or as the OP described it, "summarized"), but the OP also wrote:

I can't get perl to give me an error. I am purposely trying to insert data for a non-existant column. So it should kcik back with an error - but it is not.

I believe a better suggestion is "Post your code", not "Please add these two lines to your program, because even though I haven't seen the code and MySQL isn't giving you the error you expect, they might magically solve your problem."