Updating a view

Posted by / 31-Oct-2020 13:58

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.

If conditions later change so that the query of an invalid view can be executed, the view can be recompiled and be made valid (usable).

For information changing conditions and their impact on views, see "Managing Object Dependencies".

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 7499 ALLEN 30 SALES CHICAGO 7698 BLAKE 30 SALES CHICAGO 7654 MARTIN 30 SALES CHICAGO 7900 JAMES 30 SALES CHICAGO 7844 TURNER 30 SALES CHICAGO 7521 WARD 30 SALES CHICAGO OPERATIONS BOSTON 15 rows selected. In the case of views containing an outer join on other nested views, a table is key preserved if the view or views containing the table are merged into their outer views, all the way to the top.

A view which is being outer-joined is currently merged only if it is "simple." For example: OWNER TABLE_NAME COLUMN_NAM UPD ---------- ---------- ---------- --- SCOTT EMP_DEPT_V EMPNO NO SCOTT EMP_DEPT_V ENAME NO SCOTT EMP_DEPT_V DEPTNO NO SCOTT EMP_DEPT_V DNAME NO SCOTT EMP_DEPT_V LOC NO 5 rows selected.

Base tables might in turn be actual tables or might be views themselves.

To update a view's SQL query: flag is not demonstrated here. If you do not set a default table expiration at the dataset level, and you do not set an expiration when the view is created, the view never expires and you must delete the view manually. The examples in these sections work only if you explicitly define the primary and foreign keys in the tables, or define unique indexes.The following statements create the appropriately constrained table definitions for CREATE TABLE dept ( deptno NUMBER(4) PRIMARY KEY, dname VARCHAR2(14), loc VARCHAR2(13)); CREATE TABLE emp ( empno NUMBER(4) PRIMARY KEY, ename VARCHAR2(10), job VARCHAR2(9), mgr NUMBER(4), sal NUMBER(7,2), comm NUMBER(7,2), deptno NUMBER(2), FOREIGN KEY (DEPTNO) REFERENCES DEPT(DEPTNO)); is fundamental to understanding the restrictions on modifying join views.For example: // import "cloud.google.com/go/bigquery" // ctx := context. = nil # from google.cloud import bigquery # client = bigquery.

updating a view-33updating a view-21updating a view-24

Note: It is not necessary that the key or keys of a table be selected for it to be key preserved.