Regarding cardinality symbol used in the relational schema
Picturing the relation from sales to customers table we could say it is a many to one relationship, that being the case why was the cardinality mentioned as || near the customers table though? Could you please illustrate with an example?
Thanks for reaching out.
The first symbol which is from left to right next to the customers table is the minimum number of instances of the sales table that can be associated with the customers table. The second symbol is the maximum number of instances of the sales table that can be associated with the customers table. So, this is the reason why we have || next to the customers table.
Hope this helps.