I have a link table that I am using that has an extra column. This an example of my table structure:

Table 1
record_id
record_name
record_date

Table 2
equipment_id
equipment_name

Table 3 (Link Table)
record_id
equipment_id
type

When inserting a record how to I populate the type field that can be null from a set. Please provide an example. I can populate the two id fields but I just don't understand how I can set the values of the type when the it's a set.