Urinating only when parent is near.

I have a 4 year old girl who refuses to urinate unless a parent is nearby.  She will hold it all day.  I know this is 6-12 but please help.

[babygirl6152]

Urinating in the toilet or in diaper?
all I can think of is- the toilet is a bit scary- the noise from the flushing etc- the room is of course separate from the mainstream hubbub of the home- maybe books by the potty? one of those cute child toilets that are musical?  But they won't be everywhere/ like at school or at the market- so maybe that's not such a good idea for long term- only to shake her fears???