Zoho CRM

I have four new columns I have to populate within records that already exist. Right now, in Zoho CRM, I am using the sheet view to update 100 records at a time by copy/paste from my Excel into Zoho sheets. For 50,000+ records this is highly inefficient and costs me a lot of time. I will frequently have to update these four fields plus others as new data comes to me and right now I am stuck doing this task in the manner explained above. I am a new Zoho CRM user, so any help would be greatly appreciated.