View | Indexes | Cluster

 
View
-A virtual table (usually join >2 tables) that derived from base table.
-is not located any storage space.
-

EG
CREATE VIEW emp_view AS
SELECT empno, ename, sal, loc
FROM emp e, dept d
WHERE e.deptno = d.deptno AND d.deptno = 10;

SELECT ename
FROM emp_view
WHERE empno = 9876;

Finally

SELECT ename
FROM emp, dept
WHERE emp.deptno = dept.deptno AND
dept.deptno = 10 AND
emp.empno = 9876;

 


Indexes (optional)
-create indexes on >1 columns of a table.
-speed SQL statement execution on that table.

EG
CREATE INDEX emp_idx1 ON emp (ename, job);

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Clusters

-optional method of storing table data.
-A cluster is a group of tables that share the same data blocks because they share common columns and are often used together.

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