
It doesn't happen as often as one might expect, but every now and again I get bitten on the ass by the fact that most of my programming knowledge has been acquired on an as-I-go basis.
Today I spent far longer than necessary wondering why my lovely MySQL concatenation query kept returning NULL.
It wasn't until I did a Google search for MySQL CONCAT returns NULL that I was directed to the MySQL Manual, where I read that CONCAT always returns NULL if any of the referenced fields are NULL
In other words, I should have Read The Fine Manual to begin with.