The correct answer to perform the specified update and insert operations is to use the MERGE statement, which is designed to facilitate such "upsert" operations (update or insert).
A . The syntax is incorrect; the WHERE clause is not used with MERGE.
B . This is the correct syntax and use of the MERGE statement. It uses the ON clause to specify the join condition, and it provides actions for WHEN MATCHED and WHEN NOT MATCHED situations.
C . The keywords FOUND and NOT FOUND are not valid in the context of the MERGE statement in Oracle SQL.
D . Similar to option A, the syntax is incorrect because MERGE uses an ON clause, not a WHERE clause, and the keywords FOUND and NOT FOUND are incorrect.
The correct syntax of a MERGE statement includes defining a condition using the ON clause to determine how rows from the source and target tables are matched, then specifying the actions for when rows match (WHEN MATCHED) and when they do not match (WHEN NOT MATCHED).
Reference:
Oracle Documentation on MERGE: https://docs.oracle.com/database/121/SQLRF/statements_9016.htm#SQLRF01606