Hello!

I am working on building a month over month report for our pipeline. Essentaially I would like to compare the dollar amount in each stage of the pipeline to the previous month. Is there a formula I can use to create a feild that shows me the amount of money in each stage of the pipeline last month?

17:33:32.563 sfdx force:auth:web:login --setalias VSCodePlayground --instanceurl https://login.salesforce.com --setdefaultusername
'sfdx' is not recognized as an internal or external command,
operable program or batch file.
17:33:33.227 sfdx force:auth:web:login --setalias VSCodePlayground --instanceurl https://login.salesforce.com --setdefaultusername
 Salesforce CLI is not installed. Install it from https://developer.salesforce.com/tools/sfdxcli


How to resolve this?
Cli is installed but getting this error

I am volunteering at a nonprofit.  We have no money to buy Community licenses.  We want our volunteers to update contact and Custom Object  information in Salesforce.  What is the best way to do this?  We have no money, but I can code.  Any ideas?  Thanks.

Hello. An error message has popped up for some of my users and it's way above my head to fix. Before I turn to Premier Support our our outside support, I thought I'd try here. 
As a System Admin, I can create new Opportunities. However, those with a different profiel cannot. I've attached a jpeg of the error message. I am not a Developer, so if we have to spend some money, so be it. Any help would be appreciated. 

I mised my PD1 online proctored exam due to some circumstances. Now can I take the exam again without paying money?  If not how much will i need to pay and when can I take the exam?