Explanation:
This task can be done using the MERGE command. Correct syntax for the MERGE command is MERGE INTO table1 USING table2 on (join_condition) WHEN MATCHED UPDATE SET col1 = value WHEN NOT MATCHED INSERT (column_list) values (column_values).
Incorrect Answers:
1: MERGE command can handle this task, not UPDATE: new employee details will not be added to the table
3: This statement would by correct if UPDATE SET is syntax used, not UPDATE table_name SET syntax as in usual UPDATE command.
4: “ON condition” clause of the MERGE command is absent.
OCP Introduction to Oracle 9i: SQL Exam Guide, Jason Couchman, p. 273-275
Chapter 6: Manipulating Oracle Data

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