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Asked on 15/11/2017 IT Courses/Oracle Training/Oracle Database/Oracle 11g DBA

Which course is suitable for become a DBA and where I can do certification course?

Answer

Asked on 15/11/2017 IT Courses/Oracle Training/Oracle Database/Oracle 11g DBA

Sir can you please tell me about exame pattern of DBA (OCA, OCP, OCM). If I want to write OCM exam then... read more
Sir can you please tell me about exame pattern of DBA (OCA, OCP, OCM). If I want to write OCM exam then what is the cause duration for entire course? read less

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Lesson Posted on 29/09/2017 IT Courses/Oracle Training/Oracle Database/Oracle 10g DBA

Basic understanding of DBMS and RDBMS and Database and its Architecture

Ghanshyam M

I am Consultant and Trainer, with over 7 years of experience as Oracle Technical Consultant and trainer...

What is Data:- The data is stored representation of objects and events which has the meaning .It can be structured or unstructured. What is Information:-It is the data in the processed form which will increase the knowledge of end user. What is Metadata:-It is the data which describes the properties... read more

What is Data:-

The data is stored representation of objects and events which has the meaning .It can be structured or unstructured.

What is Information:-It is the data in the processed form which will increase the knowledge of end user.

What is Metadata:-It is the data which describes the properties or characteristics of the user data and its context.

What is database:-Database is the collection of data in one or more data file.

DBMS:-Database management system is the software which is used to create or manage the database and provides the controlled access to the database.

Database from Oracle point of View:-Database is the collection of data in one or more data file.

It is the collection of Logical structure and Physical Structure which are configured to maintain the integrity of the system.

Logical structured:-In the database State, The Logical structured are the representation of the actual metadata which are in the form of Table space, data dictionary.

Table space:- It is invisible in nature and bridge between the oracle database and Data File structure.

Data dictionary: - It is also a logical structure which basically captures the metadata of the Objects.

Physical Structure: - In the database State, The Physical structure are in the form of Table,synonym,view etc.

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Asked on 05/09/2017 IT Courses/Oracle Training/Oracle Database/Oracle 10g DBA

Im a DBA with just the basic skills hence I got no confidence to face an interview. As a result Im stuck... read more
Im a DBA with just the basic skills hence I got no confidence to face an interview. As a result Im stuck in the same company for 4.5 yrs with no progress Financially or Technology skills. Please help me in deciding what to do next etc. read less

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Lesson Posted on 23/08/2017 IT Courses/SQL Programming IT Courses/Oracle Training/Oracle Database/Oracle 11g DBA

Virtual (Derived) Column: Oracle 11g R1 (Part 1)

Arun

I have more than 6 years of industry experience in Oracle sql plsql real time development and currently...

VIRTUAL OR DERIVED COLUMN A nice feature introduced in Oracle 11gR1. Welcome to the practical analysis of various scenarios with virtual columns - introduced in 11gR1 are like normal table columns whose values are derived from other columns. Creating table with virtual column DROP TABLE t_virtual_test1... read more

VIRTUAL OR DERIVED COLUMN

A nice feature introduced in Oracle 11gR1. Welcome to the practical analysis of various scenarios with virtual columns - introduced in 11gR1 are like normal table columns whose values are derived from other columns. 

  • Creating table with virtual column

DROP TABLE t_virtual_test1 PURGE;
CREATE TABLE t_virtual_test1
(
salary NUMBER,
commission NUMBER,
total NUMBER GENERATED ALWAYS AS (salary + commission) VIRTUAL
);

  • Inserting values into virtual columns

INSERT INTO t_virtual_test1 (salary, commission) VALUES (10000,999);
COMMIT;

The third column (which is virtual/derived) is auto derived (not auto populated).

SELECT * FROM t_virtual_test1;

SALARY COMMISSION TOTAL
10000 999 10999

We will see difference between auto derivation and auto population in later sections. Actually, the above logic is same as deriving values in SELECT like

SELECT salary, commission, salary + commission total FROM t_virtual_test1;

We will try out different scenarios starting with the below INSERT. Any guess about the value in the virtual column TOTAL?

INSERT INTO t_virtual_test1 (salary, commission) VALUES (20000,NULL);
COMMIT;

SELECT * FROM t_virtual_test1;

SALARY COMMISSION TOTAL
Rs. 10000 null null
  • Data dictionary view

As a developer/DBA, it is important to get to know the data dictionary details corresponding to each new concept your are learning. For virtual columns, we can check the column DATA_DEFAULT in data dictionary USER_TAB_COLUMNS

TABLE_NAME COLUMN_NAME DATA_TYPE DATA_DEFAULT
T_VIRTUAL_TEST1 SALARY NUMBER null
T_VIRTUAL_TEST1 COMMISSION NUMBER null
T_VIRTUAL_TEST1 TOTAL NUMBER "SALARY"+"COMMISSION"
  • Other scenarios

* Try updating the actual columns, and when you SELECT, the virtual column value will be derived based on the new/updated/latest values in the actual columns.

UPDATE t_virtual_test1
SET commission = 111;
COMMIT;

SELECT * FROM t_virtual_test1;

* Try giving your own value for derived column. You cannot insert value for derived columns because - it is always derived.


INSERT INTO t_virtual_test1 (salary, commission, total) VALUES (10000,999,10999);

Read the error report carefully - you get so much info/clue from this report
always note the error code and error message
--ORA-54013:Insert operation disallowed on virtual columns

Same for UPDATE.

UPDATE t_virtual_test1 SET total = 4444 WHERE salary = 10000;

error - Update operation disallowed on virtual columns

* Is there any way to include derived column name in INSERT?

yes - we can use the DEFAULT keyword (DEFAULT - is a basic concept which we normally use in our DMLs to instruct Oracle to go by default settings given during table creation. Please search and learn more about default).

INSERT INTO t_virtual_test1 (salary, commission, total) VALUES (11,22,DEFAULT);
COMMIT;

Note: Using DEFAULT in UPDATE will not work for virtual columns

  • Variations in virtual column creation Syntax

Above points discussed gives an overview of Virtual column. Now we will look into the optional syntax keywords and what will happen if we ignore those keywords while virtual column creation

* We can omit the datatype of virtual column - datatype is auto set based on the expression given,       like (salary + commission) gives a NUMBER in below example

DROP TABLE t_virtual_test2 PURGE;
CREATE TABLE t_virtual_test2
(
salary NUMBER,
commission NUMBER,
total GENERATED ALWAYS AS (salary + commission) VIRTUAL
);

DESC t_virtual_test2

SALARY          NUMBER
COMMISSION NUMBER
TOTAL            NUMBER

 * GENERATED ALWAYS and VIRTUAL keywords are optional

DROP TABLE t_virtual_test3 PURGE;
CREATE TABLE t_virtual_test3
(
salary NUMBER,
commission NUMBER,
total AS (salary + commission)
);


INSERT INTO t_virtual_Test3 VALUES (10000,300,default);
COMMIT;

Keep you updated in next post.

I keep my posts designed in such a way that the contents are more program oriented. The program speaks volumes. I welcome your suggestions and reviews to update my style.

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Asked on 19/08/2017 IT Courses/Oracle Training/Oracle Database/Oracle 11g DBA

I am Oracle database 11g, 12c and RAC trainer looking for an opportunity as trainer.

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Answered on 15/09/2017 IT Courses/Oracle Training/Oracle Forms IT Courses/Oracle Training/Oracle Database/Oracle 11g DBA

I am looking to learn oracle forms and reports not in terms of theoretical training, As I want to work... read more
I am looking to learn oracle forms and reports not in terms of theoretical training, As I want to work in a project base training. Those who have completed a Oracle project on your own can please guide me how to work in a real time project? read less

Prakash Reddy

Yes, Oracle Forms is front-end tool for rapid development and it uses PL/SQL code in forms . You should know pl/sql before jumping to Forms and even it supports Java beans, jars etc.. It's tight integration with Oracle Database. Now Forms is part of Oracle Fusion Middle, latest version is 12c. By default... read more
Yes, Oracle Forms is front-end tool for rapid development and it uses PL/SQL code in forms . You should know pl/sql before jumping to Forms and even it supports Java beans, jars etc.. It's tight integration with Oracle Database. Now Forms is part of Oracle Fusion Middle, latest version is 12c. By default for basic DML operations without any code also it will take care by itself to insert, update, delete etc,,, it can be called as intelligent Tool. read less
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Lesson Posted on 14/06/2017 IT Courses/Oracle Training/Oracle Database IT Courses/Oracle Training/Oracle Database/Oracle 11g DBA IT Courses/IT Certifications/Oracle Certification/Oracle DBA OCA

How To Prepare For OCA Exam?

Anupam Thakur

I am a Technical Architect having 14 years of experience in Oracle database and currently working in...

Oracle Certified Associate certification programs are very costly to take the exam. They really deserve it because you get a high value of this certification in the job market. This Article is meant for ideas or steps you can take while preparing for the exam.Most of us keep on preparing ourselves to... read more

Oracle Certified Associate certification programs are very costly to take the exam. They really deserve it because you get a high value of this certification in the job market. This Article is meant for ideas or steps you can take while preparing for the exam.

Most of us keep on preparing ourselves to take the test month after month and even a year passes but really do not get the confidence to sit for the exam. I am also among these types of guys. So whatever I am going to say here is fully from my personal experiences. After I went on preparing for OCA day after day, month after month I realise that I am not able to get the good percentage of marks in the self-assessments mock tests. The reason is that I followed many OCA books and exhaustively studied each of the books. Following so many books at the same time actually confused my conceptions in Oracle! Now preparing for the OCA exam in between my daily works and job became difficult for me, so I just consulted one of my seniors and we came up with great ideas.

We decided to follow the following rules to prepare for the OCA Exam so that I go to the track and take the test very soon and accurately:

  • Do not follow many books at the same time. Just read only one book prescribed for the OCA Exam.
  • Keep aside at least 2 hours for the preparation, from your busy schedule.
  • Concentrate on each Chapter very clearly and make notes for the important tips mentioned in each chapter.
  • Take the self-assessment test provided at the end of each chapter very honestly.
  • Proceed to the next chapter only if you feel that you are comfortable with the previous chapter.
  • Make notes with step by step instructions for the exercises in each chapter, separately. So you now have two types of notes, one for the Important Tips and the other for Exercises.
  • Now as you proceed chapter by chapter, do always remember to overview the exercises at a later stage. This will help you memorise the commands used in your exercises.

If you sincerely follow the steps above, I hope you can find yourself in a good position to take the OCA Exam.

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Answered on 13/10/2016 IT Courses/Oracle Training/Oracle Database IT Courses

Srijit Dutta

Expert PHP and ORACLE tutor with 7 years of experience

Oak Ridge Automatic Computer and Logical Engine
Answers 19 Comments
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