help with string

[fromhell]

greeting all
i need help from you guys
i develop a system where user can upload a file.
for avoid the user from overwrite the existing file, i hardcode all the title will be insert to the database similar to this format..for example if user upload file name "test.doc", the file will be name "test_12345678912.doc"..the number is date and time.

so,
what i'm gonna do is..
when displaying the title..i want to remove __12345678912.doc
can someone help me?

one more thing..from the database, when displaying address, it give " "

can someone help me to remove it?

thanks in advance