The issue, I believe, is that 'SHOW' is a reserved word in MySQL (eg: SHOW ALL TABLES

so it gets very confused if it shows up unquoted (in backticks).
I'm all for changing the name of that column - we really shouldn't use reserved words even if we do make sure to quote them, it's just not good practice.
For now, you can find some way to quote the column name, so it'd look something like `'zp_images'.'show'` (except - the single quotes should be backticks, but this forum won't show them since it uses that for code notation).