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In this case, the view is considered "created with errors." For example, when a view is created that refers to a nonexistent table or an invalid column of an existing table, or when the view owner does not have the required privileges, the view can be created anyway and entered into the data dictionary. To create a view with errors, you must include the .

When you try to create such a view, the database returns a message indicating the view was created with errors.

A new primary key value can be obtained by selecting the most recently produced value and incrementing it.

This method requires a lock during the transaction and causes multiple users to wait for the next value of the primary key; this waiting is known as .

EMPNO ENAME DEPTNO DNAME LOC ---------- ---------- ------- -------------- ----------- 7782 CLARK 10 ACCOUNTING NEW YORK 7839 KING 10 ACCOUNTING NEW YORK 7934 MILLER 10 ACCOUNTING NEW YORK 7369 SMITH 20 RESEARCH DALLAS 7876 ADAMS 20 RESEARCH DALLAS 7902 FORD 20 RESEARCH DALLAS 7788 SCOTT 20 RESEARCH DALLAS 7566 JONES 20 RESEARCH DALLAS 8 rows selected.

operation is permitted, because although there are two key-preserved tables, they are the same table. In this case, the delete statement operates on the first table in the EMPNO ENAME DEPTNO DNAME LOC ------- ---------- ------- -------------- ------------- 7369 SMITH 40 OPERATIONS BOSTON 7499 ALLEN 30 SALES CHICAGO 7566 JONES 20 RESEARCH DALLAS 7654 MARTIN 30 SALES CHICAGO 7698 BLAKE 30 SALES CHICAGO 7782 CLARK 10 ACCOUNTING NEW YORK 7788 SCOTT 20 RESEARCH DALLAS 7839 KING 10 ACCOUNTING NEW YORK 7844 TURNER 30 SALES CHICAGO 7876 ADAMS 20 RESEARCH DALLAS 7900 JAMES 30 SALES CHICAGO 7902 FORD 20 RESEARCH DALLAS 7934 MILLER 10 ACCOUNTING NEW YORK 7521 WARD 30 SALES CHICAGO 14 rows selected.

To ensure that the alteration does not affect the view or other objects that depend on it, you can explicitly recompile a view after altering one of its base tables.

Without sequences, sequential values can only be produced programmatically.A table is key-preserved if every key of the table can also be a key of the result of the join.So, a key-preserved table has its keys preserved through a join. Base tables might in turn be actual tables or might be views themselves.All operations performed on a view actually affect the base table of the view.

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You can use views in almost the same way as tables.

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