SQL full outer join – when I want to exclude intersection part, why equal is used in join condition while values are never equal?
I have rows either in table t1
or in table t2
. Both table have the common field id
and name
, and id
is either null for t1
or t2
(it cannot be in both table at the same time). Now I want to select all rows in both tables, either in t1 or in t2, as long as name
matches a pattern.