Oracle 4: View

View: A query statement that can correspond to one or more tables

-- create a view without querying payroll Create or Replace View V_normal  as Select e.empno,e.ename,e.job,e.mgr,e.hiredate  from EMP E Order  by E.hiredate

--Query results as a table to correlate queries--Views: Shows the average salary, department number, department name, average salary for each departmentCreate or Replace ViewV_avg asSelectRes.*, D.dname from(SelectE.deptno,avg(SAL) fromEMP EGroup  byE.deptno) res,dept DwhereRes.deptno=D.deptno
With Read only
--View becomes read-only

Sequence:

Oracle database provides an object called sequence

Sequence: is an object that stores a numeric value that can be set initially (default is 1) to set the next value more than the previous value (default is 1), each time the resulting value is different

--Create a sequenceCreatesequence Seq_noincrement by TenStart with  -Cache -Select *  fromDept--inserting data using department sequencesInsert  intoDeptValues(Seq_no.nextval,'Develop A','Earth')--Query SequenceSelectSeq_no.currval fromDual

Oracle 4: View