[Typo3] How to debug the TypoScripts?

[Dennis Cheung]

Hi all,

I have a problem on writing some template and typoscript.

I found CONTENT will show nothing if the select/query has any problem. But I
didn't found any errorlog/warning from anywhere.
And finally I have to enable query log in mysql to check what it had did.

Are there any debug mode or flag can temporary enable error message on web
pages without affect others pages on same typo3?

Thanks
Dennis