Hello everyone, I am trying to work out the best way to achieve the following:
I have 2 custom objects Jobs and Job Types. I would like to enable multiple job types to be linked to any job. I can link the 2 objects, which enables me to use the 'New Job Types' button to create a new job type, but I only want to be able to select from a predetermined list of Job Types and multiples of those job types.
For example: Job 001 is created and assigned to an engineer. He does the job and need to select the job types he has completed (1 x Replace power supply / 3 x reset system / 2 x Firmware updates).
I was thinking a multi-select picklist, but this would only permit 1 x of each selection. I would like to see this as related list on the Jobs object also and have a button to 'Select' job types, instead of creating new Job Type.
What is the best way to go about this? I suspect I may need to create a junction object perhaps?
Any help would be greatly appreciated.
Thanks
Matthew

Hello. I'm trying to start on the Build A Data Model for a Recruiting App Project. https://trailhead.salesforce.com/projects/build-a-data-model-for-a-recruiting-app/steps/create-a-custom-object-for-reviews It asks that I install an unmanaged package but when i click on the link provided it says the app cannot be installed because the package is not found. 
"The requested package doesn't yet exist or has been deleted. If this is a recently created package version, please try again in a few minutes or contact the package publisher."
I need to understand roll-up fields (starting from the basics) so i need to complete this or is there another, newer module that will explain it better?

Your company sells cylindrical hyperbaric chambers. You need a formula field that calculates the volume of a cylinder for you, rounded to the nearest whole number, given its radius and height. Use the existing mathematical formula for the volume of a cylinder, V = πr2h, where r is the radius of the cylinder, h is the height, and π is the constant Pi. Note: Although this formula field might best be created on a custom object, for simplicity, we’ll create this formula on the Opportunity object.
>Create 2 custom fields of type Number on the Opportunity object: ‘radius’ with a resulting API name of ‘radius__c’ and ‘height’ with a resulting API name of ‘height__c’.
>The formula should be named ‘Cylinder Volume’, with the resulting API name ‘Cylinder_Volume__c‘ and should be created on the Opportunity object.
>The formula should reference the custom fields ‘radius__c‘ and ‘height__c‘.
>The formula should use 3.14159 as an approximation of Pi.

Heres the challenge that im stuck on. i have created the 2 custom fields. What im stuck on is where do we create the formula. Do we put it in the custom fields or is there another place u insert it?

thanks if anyone can help