Outer Joins Introduce Nulls
Learn about outer joins, nulls, and what happens if the not-null constraint is not used.
We'll cover the following...
The outer joins are meant to preserve rows from our reference relation and add to it columns from the outer relation when the join condition is satisfied. When the join condition is not satisfied, the outer joins then fill the columns from the outer relation with null values.
The outer join clause and null values
A typical example would be with calendar dates when we have not yet registered data at given dates. In ...