Do I need an eTA after I got approved for Study Permit?

[jhoongo]

Hi,

Just a simple question, I've got the approval for my study permit and am planning to enter Canada next week.
Do I still need to apply for eTA? I've applied for eTA today just in case, but it is still pending for few hours.
If this eTA application goes wrong, will this affect acquiring study permit while I enter?

Any help or suggestion is appreciated.

Thanks,