Knowing if a custom field is empty or not

[exclusif]

Hello,

I wanted to know if it exists a column in the different tables of Mantis, which permit to determine whether a custom field is filled or not. Moreover, i need to split

this for each project.

I hope that it's possible without searching in the source code of Mantis, because i need to make some statistics with this attribute in Business Object.

Thanks and have a good day