joins in sql

[Shrutibhatnagar]

hello ,

if i have 2 tables containing product id as unique id , can i say that the left and the right joins of these two tables using product id with distinct  ,can i prove that these two have product id as unique id if left and right joins  have equal number of records ? .

[Kurt_Bremser · Accepted solution]

The best proof for uniqueness is a sort with nodupkey. If that does not delete any duplicates, you have unique keys.