My Opportunities have a lookup field (Lookup__c) to specific Accounts. I have a related list of these Opportunities on these Accounts. Now, I need a custom field (Qty_of_Opportunities__c) on my Account that has the count of Opportunities in that related list. Rollup Summaries won't work as this isn't a master-detail relationship, it's a lookup. This custom field will be used in reports.
From my googling, looks like I'm going to need a trigger but I've never written or implemented one. Any help is appreciated.
