Introduction to Oracle [strongly recommended]

Oracle's system is too huge. For Beginners, it is inevitable that they will not start to feel like they want to learn anything, and the results will not be good. So share their learning experience, we hope that the beginners will have a general understanding of Oracle and avoid detours.
 

I. Positioning

Oracle has two major parts: development and management. Development is mainly about writing stored procedures, triggers, and so on, as well as using Oracle's develop tool for form. SimilarProgramPersonnel, who need to have strong logical thinking and creative ability. I personally think it will be hard, but it is a young man. J. Management needs to have a deep understanding of the principles of Oracle databases, it has the ability to perform global operations and close thinking, and has a greater responsibility. Because a small mistake will lead down the entire database, the latter places more emphasis on experience than the former.

 

Because database management has a major responsibility, few companies are willing to ask a person who has just been in contact with Oracle to manage databases. For young people who have just graduated, they can choose development first, and then transform to database management after some experience. Of course, this depends on the actual situation of individual users.

 

 

 

Ii. Learning Methods

My method is simple: Reading, thinking, taking notes, experimenting, thinking, and taking notes.

 

After reading the theoretical things, Let me calm down and think about it. I will ask myself a few more questions and take notes on what I have learned and what I think. I will do experiments when I cannot figure out or have questions, think about how it works. Similarly, write down the experiment results. Thinking and doing experiments aims to gain a deep understanding of this knowledge point. The process of taking notes is also a process of clarifying your own ideas.

 

The learning process is to make a problem from fuzzy to clear, then from clear to fuzzy. Every change means that you have learned a new knowledge point.

 

The learning process is also from point to line, from line to network, from network to surface. When the point turns into a line, you will suddenly feel open. When the network is above, you are the master

 

Many netizens, especially beginners, have obtained questions from the Forum. Have you checked the books, studied the books, and searched the Forum before asking? This is called the inertia of thinking. When someone else answers your question, it will make it difficult for you to understand this knowledge point in a short period of time. However, through your own efforts to study it, you will not only gain a deeper understanding of this knowledge point, more importantly, the research process will improve your ability to solve and analyze problems. In general, no matter what you learn, you will not succeed.

 

Of course, beginners often go to the forum to raise questions when they encounter problems and do not know where to find information. But in my opinion, can I ask others how to analyze this question? Where can I find relevant materials? What is the answer to this question? It is better to teach people to fish than to teach them to fish.

 

 

 

Next I will talk about how to handle the problem.

 

 

 

First, you must know the official website of Oracle: www.oracle.com, which contains various Oracle versions of databases, application tools, and authoritative official documents. Second, you need to know. Then there are some famous websites: asktom.oracle.com www.orafaq.net and www.dbazine.com. There are many experiences here.

 

 

 

Encountered a problem. If it is a conceptual issue, you can first find tahiti.oracle.com. Here we will give you the most detailed explanation. If any errors occur during the running process. You can go to Metalink. If you want to know the experience of transaction processing. You can go to asktom. Of course. This is just relative.

 

 

 

 

 

 

Iii. Oracle System

Oracle has a huge system. To learn about it, you must first understand the Oracle framework. Here, we will give a brief introduction to the Oracle architecture, so that beginners can have a general understanding of oracle.

 

1. Physical Structure (composed of control files, data files, redo log files, parameter files, archive files, and password files)

Control File: contains necessary information to maintain and verify the integrity of the database. For example, a control file is used to identify data files and redo log files. A database requires at least one control file.

Data Files: data files

Redo log file: contains the changes made to the database, so that data recovery can be enabled in case of a fault. A database requires at least two redo log files.

Parameter file: defines the features of Oracle routines. For example, it contains parameters for adjusting some memory structures in SGA.

Archive file: an offline copy of the redo log file, which may be necessary to recover from a media failure.

Password File: Authenticate which users have the permission to start and close Oracle routines

 

2. Logical Structure (tablespace, segment, partition, block)

Table space: a set of data files in the basic logical structure of the database.

Segment: space occupied by objects in the database

ZONE: A large storage space reserved for data at one time.

Block: the most basic storage unit of Oracle. It is specified when the database is created.

 

3. Memory Allocation (SGA and PGA)

SGA is the memory area used to store database information, which is shared by database processes. It contains data and control information of the Oracle server. It is allocated in the actual memory of the computer where the Oracle server resides. If the actual memory is insufficient, it is written into the virtual memory.

PGA: contains the data and control information of a single server process or a single background process. The SGA shared with several processes is the opposite. PGA is only used by one process, PGA is allocated during Process Creation and recycled upon Process Termination

 

4. background processes (Data Writing Process, log writing process, system monitoring, process monitoring, Checkpoint Process, archiving process, service process, and user process)

Data Writing Process: responsible for writing changed data from the database buffer cache to the data file

Log writing process: writes changes in the redo log buffer to online redo log files.

System Monitoring: Checks Database Consistency and starts database recovery when the database is opened if necessary.

Process Monitoring: clears resources when an oracle process fails.

Checkpoint Process: updates the database status information in control files and data files whenever changes in the buffer cache are permanently recorded in the database.

Archiving process: backs up or archives a full log group during each log switch.

Service Process: User process service.

User process: On the client, the user is responsible for passing the user's SQL statement to the service process and retrieving the query data from the server segment.

 

5. Oracle routine: The Oracle routine consists of the SGA memory structure and background processes used to manage the database. A routine can only open and use one database at a time.

 

6. SCN (System Change number): System Change number, a serial number maintained by the system. It is automatically added when the system needs to be updated. It is an important indicator of maintaining data consistency and sequential recovery in the system.

 

 

 

 

 

 

4. Deep Learning

Management: You can take an examination of the OCP certificate. First, you can have a system for Oracle, and then read Oracle concepts and Oracle online document. You will have a deeper understanding of the Oracle principles, at the same time, you can start some special studies, such as rman, Ras, statspact, dataguard, tuning, backup & amp; recover, and so on.

 

Development: for Oracle development, after learning about the basic architecture of Oracle, you can focus on PL/SQL and Oracle development tools. PL/SQL mainly includes how to write SQL statements, how to use ORACLE functions, How to Write stored procedures, stored functions, and triggers. Oracle's development tools are mainly Oracle's Developer Suite (Oracle Forms developer and reports Developer) and learn how to use these tools skillfully.

 

 

 

 

 

 

Introduction to several good oracle books

 

 

 

Oracle official document: concept describes the system and concept of Oracle, which is suitable for beginners.

 

 

 

OCP teaching book, that is, study guide (SG ).

Oracle8i Backup recovery manual

Oracle8 advanced management and optimization

Oracle8i PLSQL Program Design

Oracle8 Database Administrator Manual

These books are published by the Mechanical Industry Publishing House.

 

Introduction to several websites

Official documents for http://tahiti.oracle.com Oracle

Http://metalink.oracle.com/Oracle technical support website. You must purchase the Oracle service to have an account before you can log on. You have a lot of knowledge base and experience in problem solving.

Http://www.oracle.com Oracle official website, where you can go down Oracle software, official documentation and get the latest news

Journal of http://www.dbazine.com/Oracle

Http://asktom.oracle.com

Http://www.orafaq.net/

Http://www.ixora.com.au/

Http://www.oracle-base.com

Http://www.dba-oracle.com/oracle_links.htm