Creating a new Lookup Column
Lookup columns can be created, if there is a many-to-one relation between tables. These columns can be added to the Details table to represent a specific data from a related Master table (for example, the Projects table may need to contain the Client Company, Client Phone, Client E-mail from the related Clients table).
Using one relation you can add as many lookup columns as you need.
Usually, when a reference column of Many-To-One cardinality is created and a Proxy column is chosen in the reference column settings, the lookup column displaying Proxy column values is added to a table automatically.
The simplest way to add a lookup column to a related table is the following:
Click the Setup link in the top right corner of the window
Select a table you need.
From the setup menu select Column > Create a new lookup column.
In the References section click the Add Lookup button near a necessary relation:
The Lookup column form will be displayed:
Please note, if a lookup refers to a column of the File Attachment type and the Display As Link option is unchecked in the lookup settings, a user, who clicks on such lookup, will be redirected to the attached document or image. Moreover, if an image (or a signature) is attached, this image (or signature) will be shown as a lookup value. In case the Display As Link checkbox is activated, only the link referring to the master record will be displayed as a lookup value. After clicking on such link, the master record keeping the attachment will be opened.
Moreover, in case you need to create a lookup column displaying another lookup showing an image kept in a File Attachment column, you also have to activated the Allow Public Access option in the File Attachment column settings, otherwise the image will not be visible in such lookups that display other lookup columns.