Explanation:
A view can be created as read only object. However, it is possible to change data in the underlying table(s) with some restrictions.A view also can be created as a join on two or more tables. This type of view is called complex view. Complex views provide complicated data models where many base tables are drawn together into one virtual table.
Incorrect Answers:
3: Query operations containing ORDER BY clause are also permitted, so long as the ORDER BY clause appearsoutside the parentheses. The following is an example of what I mean: CREATE VIEW my_view AS (SELECT*FROM emp) ORDER BYempno.
4: A view can be created with a GROUP BY clause in the SELECT statement.
5: It is not required to have aliases defined for the column names in the SELECT statement.
OCP Introduction to Oracle 9i: SQL Exam Guide, Jason Couchman, p. 292-309
Chapter 7: Creating Other Database Objects in Oracle

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