Self joins in Oracle Database 12c SQL have these characteristics:
* Option D: They can use INNER JOIN and LEFT JOIN.
* Self joins can indeed use various join types, including inner and left outer joins. A self join is a regular join, but the table is joined with itself.
* Option E: They require table aliases.
* When a table is joined to itself, aliases are required to distinguish between the different instances of the same table within the same query.
Options A, B, C, and F are incorrect:
* Option A is incorrect because self joins can be non-equijoins as well.
* Option B is incorrect because self joins do not require the NOT EXISTS operator. They may require a condition, but NOT EXISTS is not a necessity.
* Option C is incorrect because a join condition is needed to relate the two instances of the same table in a self join.
* Option F is incorrect for the same reason as B; the EXISTS operator is not a requirement for self joins.