My guess is that you're trying to call this function like:
update_table(pben, somePassword)
That attempts to pass the contents of the variable named pben or the result of calling a function named pben with 0 input arguments and 1 output argument into update_table. If you want to pass the literal text pben into the function, you need to specify it as a char vector or as a string.
update_table('pben', somePassword)
update_table("pben", somePassword)
If your password is not stored in a variable named somePassword but is the literal text somePassword, you need to pass that in as text as well.
update_table('pben', 'somePassword')
update_table("pben", "somePassword")