Database Oracle Basic

Nibble Matrix
By Kamlesh Kumar Singh
Database - Collection of data files.
DataFile - collection of records(rows).
Record(rows) - collection of fields.
Field = set of informations.
DBMS - Database Management System.
A System which manage the database.
Database Handler - each & every database has one database handler - that handle uthe database.
DBMS - Database Management System. - Access / FoxPro / Excel
RDBMS - Relational Database Management System. - SQL Server / Oracle upto 7.3 / sybase / MySQL.
ORDBMS - Object Relational Database Management System. - Oracle8
oracle8 - Object, user define composite data types.
OODBMS - Object Oriented Database Management System. - Oracle 8i & 9i & 10G
i - internet programming. - java is a kind of internet programming.
need for java - JVM , Oracle8i - JVM include - SQLJ - SQL Java programming.
SQL - Structured Query Language - common language for all Databases.
SQL -
DDL - create / alter / drop, truncate
DML - delete / insert / update

DCL - grant / revoke
DRL - select statement
TCL - commit / rollback / savepoint.
Codd's Rules - 12 rules + 1 zero rule = 13 rules .
Codd's -
< 6 rules support - DBMS
>= 6 rules support - RDBMS.
Oracle support 12.5 rules.
.5 not supported by oracle that is view updation.
views -
simple view & complex view
auto updation - simple views updatable but complex view - not auto updatable.
work with Oracle
env -

SQLPLUS - Oracle env
ISQLPLUS - in 9i , for use oracle with web browser. ie - http://localhost/isqlplus
--to create own database table.
1- without constraints 2 - with constraints
constraints -
not null - user can't insert into null values.
unique - not null + not duplicate
primary key - not null + not duplicate = can ref with other table
foreign or reference key - child records.
check - condition check at the DML operator(insert & update) time.
default - if user not spacify value for a column then
default value to be inserted.
constraints name -
database server assign (auto) user (explicit)

data type
number(4) - int only
number(7,2) - floating value 99999.99
char - fixed length
varchar & varchar2 - dynamic , but has max limit
lob - upto 4 gb
long - upto 2 gb
date - for date & time.
user define composite data type - Object.
- to add constraints in table .
1 - at the table creation time
2 - after table creation.
-- to create a table without constraints.
create table semp
(
empno number(4),
ename varchar(20),
sal number(7,2),
deptno number(2)
)
-- to create a table with constraints.

create table femp
(
empno number(4) constraints myno primary key,
ename varchar(20) not null,
sal number(7,2) constraints mysal check(sal> 5000),
deptno number(2) default(10) check(deptno in(10,20,30,40))
)
- to insert default value in table column
insert into cemp(empno,ename,sal) values(1003,'Amar',9299);
- to add extra column in table
alter table cemp add jdate date
- to change the column size
alter table cemp modify sal number(8,2)
*** but for decreasing column size table should be empty

- to add constraint after table creation.
alter table bemp add constraints mys check(sal<50000)
- to enable or desable constaints
- for disable
alter table cemp disable constraints mysal;
- for enable
alter table femp enable constraints mysal;
*** for enabling constraints condition must be fullfil
- to drop a constraints
alter table femp drop constraints mysal
- to set unused column
alter table cemp set unused column jdate
- to drop all unused columns

alter table cemp drop unused columns
- to drop an column
alter table cemp drop column deptno
- to rename table
rename cemp to cc;
- to create synonym
create synonym c for femp
- to create table with foreign key
create table fincr
(
empno number(4) references femp(empno),
amount number(5)
)
-
create table fbonus

(
empno number(4) references femp(empno) on delete cascade,
amount number(5) )
on delete cascade option - if parent record deleted then child record auto deleted.
else delete child record first then parent record deleted.
Joins - to select data from more then one tables.
type -
1- Equi Join - when common column exist in both tables.
select empno,ename,sal,e.deptno,dname from emp e,dept d
where e.deptno=d.deptno
2- Non Equi Join - when common column not exist in both table.
select empno,ename,sal,grade from emp,salgrade
where sal between losal and hisal
3- Cross Join - table join without any condition.
result - Ist table each row * each row of IInd table

4- Outer Join - like equi join.
Left Outer join - display those record also which r
exist in IInd not exist in Ist.
where e.deptno=d.deptno(+)
10
20
30
40 - not 50
Right outer join - display those record also which r
exist in Ist not exist in IInd.
where e.deptno(+)=d.deptno
10
20
30
50 - not 40
5- Self Join - when one table use a multiple table.

- list of all emp with his/her manager name.
select e.ename,m.ename as manager from emp e,emp m
where e.mgr = m.empno
- List of all emp whose sal > their manager.
select e.ename,m.ename as manager from emp e,emp m
where e.mgr = m.empno and e.sal > m.sal
- List of all emp who join company before their manager.
VIEWS :->
-----
* A view is a logical table based on a table or another view.
* A view contains no data of its own. but it is like a window
through witch data from table can be viewed or change.
* The tables on which a view is based are called base tables.
* the view is stored as a select statement in the data dictionary.
* the changes in the table are automatically reflected in the views.
Advantages of a view : ->
* to make a complex queries easy.
* to allow data independence .
* securities.

views types ->
1> Simple 2> complex
Deff. between Simple & complex views : -
------------------------------------
Feature Simple Complex
1> no. of tables one one or more
2> contain function no yes
3> contain groups no yes
of data
4> DML through views yes not allowed
view type
simple view - with single table
complex view - with more then one table or with functions
read only view - read only.
force view - view created without having base table

in line view - when select statement pass as a object in from clause
Q1. -> create a view, amit, that contains details of employees in deptno 10 .
Ans.
create or replace view amit as select empno,ename,sal,deptno from emp
where deptno=10;
with read only option. - > to used for create a read only view
---------------------
Q2. -> create read only view for employees of dept 10 ?
Ans. ->
create view nnn as select empno,ename,sal from emp
where deptno=10 with read only;
with check option --> when the WITH CHECK OPTION CLAUSE is used , any DML statement that
----------------- manipulate rows that can be not be selected by a VIEW ,are rejected

** to create a view with check option -
create view a2 as select empno,ename,sal,deptno from emp
where deptno=10 with check option;
* in this view we can insert only in dept 10 not in any other depts.
* to select data from a view
select * from viewname;
* to create a complex view .
CREATE VIEW CCC3 AS SELECT EMPNO,ENAME,SAL,E.DEPTNO,D.DNAME FROM EMP E,DEPT D
* create table with keys(primary key , Foreign key)
-->with Primary key
CREATE TABLE M_DEPT
(
DEPTNO NUMBER(2) CONSTRAINTS DE PRIMARY KEY,
DNAME VARCHAR2(10) NOT NULL
);
--> with foreign key

CREATE TABLE M_EMP
(
EMPNO NUMBER(4) PRIMARY KEY,
ENAME VARCHAR2(10),
SAL NUMBER(7,2),
DEPTNO NUMBER(2),
FOREIGN KEY(DEPTNO) REFERENCES M_DEPT(DEPTNO)
);
--> create view
CREATE VIEW CCC4 AS SELECT EMPNO,ENAME,SAL,E.DEPTNO,D.DNAME FROM M_EMP E,M_DEPT D
WHERE E.DEPTNO=D.DEPTNO
-- force view - view create without a base table.
create force view amit6 as select * from baba
--------->
The view must not contain any of the following constructs:
A set operator
A DISTINCT operator
An aggregate or analytic function
A GROUP BY, ORDER BY, MODEL, CONNECT BY, or START WITH clause

A collection expression in a SELECT list
A subquery in a SELECT list
A subquery designated WITH READ ONLY
An inline view is a SELECT statement in the FROM-clause of another SELECT statement. In-line views are
commonly used
simplify complex queries by removing join operations and condensing several separate queries into a
single query.
This feature was introduced in Oracle 7.2.
This feature is commonly referred to in the MSSQL community as a derived table, and in the Postgres
community
simply refers to it as a subselect (subselects are inline views + subqueries in Oracle nomenclature).
[edit]Examples
Example inline view:
SELECT *
FROM ( SELECT deptno, count(*) emp_count
FROM emp
GROUP BY deptno ) emp,
dept
WHERE dept.deptno = emp.deptno;
Another good example of an inline view is:
SELECT a.last_name, a.salary, a.department_id, b.maxsal
FROM employees a,
( SELECT department_id, max(salary) maxsal
FROM employees

GROUP BY department_id ) b
WHERE a.department_id = b.department_id
AND a.salary = b.maxsal;
Materialized view or snapshot-> it is one kind of physical table not a logical table.
automatic updation not allowed.
*to create a Materialized view ->
create materialized view cc2 as select * from m_emp;
or
create snapshot cc2 as select * from m_emp
-to drop a materialized view
drop materialized view viewname
* Materialized view not created if table does not contain a primary key constraint.
* for creating materialized view user should have dba privileges.
the DBA can create a user by using the create user command, once a user
is created the DBA can grant the specific system privileges to a user.

Schema - collection of Objects such as tables / views & sequences.
user schema - collection of users Object.
Data Securities -
System Securities - System privileges - gain access to the database.
Data Securities - Object privileges - manipulates the content of
the database Objects.
Object privileges vary from Object to Objects.
Role - group of privileges , role is a kind of intermediate user.
oracle server provide the 3 standard role.
connect - to connect with database
resource - to use the data base resources
dba - for DBA task (database Administration )
- to create user define role -
create role baba;

grant create session,create table , create procedure to baba;
grant baba to singh;
-- TO DROP A ROLE
DROP ROLE BABA
Grant - to assign the privileges
revoke - to remove the privileges.
System privileges -
create session - for connect
create table - for create table
create view - for view creation
create sequence - for sequence creation
create procedure. - for function , procedure & package creation
unlimited tablespace

Object privileges -
privileges table view sequence procedure
alter y - y -
delete Y Y - -
execute - - - Y
index Y - - -
insert Y Y - -
references Y - - -
select Y Y Y -
update Y Y - -
=
all
public - for all users
** for DBA - user should have DBA privilege.
-- to display list of all existsing.
select * from all_user.
-- to create a new user

create user username identified by password
-- to change the password
alter user username identified by password;
-- for connecting user should have connect / create session
privilege.
-- to assign Object privileges -
grant select , insert , update on emp to singh.
grant all on emp to public - for all user
public - for all users
grant select , insert , update on emp to singh
-- TO DROP A USER
DROP USER USERNAME
DROP USER USERNAME CASCADE - DROP USER WITH ALL RELATED LINKS

- for assign Object privileges
grant select,insert , update on emp to singh;
grant select,insert , update on emp to public; -- to assign select , insert & update
privilege for all user.
grant all on emp to public; -- to assign all privileges for all user.
-- to revoke the Object privileges -
revoke select , insert , update on emp from singh;
with grant Option - Object privileges granted with grant option r
revoked when the granter's previleges is revoked.
sequence - sequence is used for auto number generation ,for serial no ,

rollno / empno & more.
syn -
create sequence my
start witn 1001
increment by 1
minvalue 1001
maxvalue 1010
cycle
cache 3
attributes for sequence -
nextval - next value from sequence
currval - current value in sequence
-- to alter seqnence
alter sequence mys
increment by 2
maxvalue 1020
cycle

select ab.nextval from dual
-- to use sequence in table
insert into emp values(ab.nextval,'&name',&sal)
-- to drop a sequence
drop sequence ab;
-- to display list of all sequence
select * from user_sequences;
Temporary Table :-
---------------
used for Temporary result.data exist only for the duration of a transction or session .

only visible with in a single transaction or session. no redo generated.
created in user's temporary tablespace.
syn:-
create global temporary table ab
(
eno number(4) primary key,
ename char(22)
)
on commit delete rows
this table is for transction duration.
* no data segment created.
Indexing - An Oracle Server Index is a Schema Object that can speed
up the retrieval of row by using a pointer. Indexes can be
created explicit & implicit.
if U do not have index on the column, then a full table scan will occur.
implicit index - ORACLE itself creates indexes at the time of
table creation, if a table definition contains a PRIMARY KEY.
Explicit Index - that is created by user.

create [UNIQUE] index INDEXNAME on TABLENAME[COLNAME];
*** to display list of all user indexes.
select * from user_indexes;
CLUSTERING -
=> Clusters r used for performance improvement.
=> Clustering is a method of storing tables that r related and
often accessed together.
=> A cluster is group of rows from separate tables storing in the
same disk block.
=> Clustered tables must have a common column called cluster column.
=> to Cluster tables the user must own the tables.
*** if table is the part of cluster can't be partition.
steps for creating clusters -
=> creating cluster

create cluster cname(colname datatype)
=> creating cluster tables
create table tname
(
colname datatype primary key,
colname datattype
)cluster cname(colname)
create table tname
(
colname datatype references tname(colname),
colname datattype
)cluster cname(colname)
=> creating cluster indexes.
=> In a clustered index, the actual data is stored in the indexed order.
=> Each Unique cluster key value is stored only once in the each data
block.
=> they save disk space and improve perforence for many operations.
syn -
create index iname on cluster cname;

=> to drop an cluster
drop cluster cname;
*** cluster not deleted if cluster is not empty.
drop cluster cname including tables ;
drop cluster cname including tables cascade constraints ;
=>

Database Oracle Basic

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Database Oracle Basic