Introduction to Oracle Database Administration
Introduction to Oracle Database Administration.
What is Oracle?
Oracle database is a relational database management system (RDBMS) from Oracle Corporation. This article will explain a complete overview of the Oracle database, features, history, and editions. Before discussing the oracle, we will first need to know about the database.
What is database?
A database refers to the organized collection of structured data stored electronically in a device. It allows us to access, manage, and find relevant information frequently. The flat file structure was extensively used to store data before the database system was invented. The relational database approach becomes popular in comparison to the flat file model because it eliminates redundant data. For example, suppose we have an employee and contact information stored in the same file. In such a case, the employees with multiple contacts will show up in many rows.
The RDBMS system manages the relational data. Oracle Database is the most famous relational database system (RDBMS) because it shares the largest part of a market among other relational databases. Some other popular relational databases are MySQL, DB2, SQL Server, PostgreSQL, etc.
What is the Oracle database?
Oracle database is a relational database management system. It is also called OracleDB, or simply Oracle. It is produced and marketed by Oracle Corporation. It was created in 1977 by Lawrence Ellison and other engineers. It is one of the most popular relational database engines in the IT market for storing, organizing, and retrieving data.
Oracle database was the first DB that designed for enterprise grid computing and data warehousing. Enterprise grid computing provides the most flexible and cost-effective way to manage information and applications. It uses SQL queries as a language for interacting with the database.
Edition of Oracle database
The following is a list of Oracle database editions in order of priority:
- Enterprise Edition: It is the most robust and secure edition. It offers all features, including superior performance and security. It is liscense based.
- Standard Edition: It provides the base functionality for users that do not require Enterprise Edition’s robust package. It is liscense based.
- Express Edition (XE): It is the lightweight, free and limited Windows, and Linux edition. It is free of cost.
- Oracle Lite: It is designed for mobile devices.
- Personal Edition: It’s comparable to the Enterprise Edition but without the Oracle Real Application Clusters feature.
à Oracle starting version is 19C, It is a stayable version and it will support till 2027.
àOracle 19.3.0.0.0 is a base version in 19C. It means on any flavour we can install 19.3 version.
àPatching: It means we can upgrade the Oracle version in 19.3 and automatically it will upgrade into the required version.
Oracle 19c Installation Process:
Step 1: Search Oracle 19.3 version for Microsoft window X64(64-bit) in google
Step 2: After downloading Extract the file
Step 3: After extracting the files, create the folders in hierarchy i.e.,
- App
- Oracle
- Product
- 19C
- Db_home
Step 4: After creating folders, Click on setup wizard
Step 5: Search in start box i.e., (Oracle)
Step 6: Verify in services i.e., (OracleserviceORCL–> this is default name) Here Database name is ORCL and Software name is Oracle service.
Step 7: Search SQL plus
Step 8: Connect to database.
Step 9: Enter username : /as sysdba
If we are installing oracle for the first time in the server by default it will take database name as ORCL
If we are doing oracle installation more than one time then every time we need to change the database name.
Ex: orcl21c, orcl23c etc.,
Important points about errors in Oracle
- Error description is different for every error i.e., error code, error name etc.
- Error description is also very important.
- Oracle database should be always in running mode.
Compatibility matrix: It means operating system and database version compatibility. Both need to be compatible.
Virtual Box: Multiple servers on physical server is known as Virtual Box.
Oracle 21c installing process:
It is same as oracle 19c process
After installing 21c when we type SQL plus in search box it is opening in 19 version and it will show error.
To get into 21c version in SQL plus then the process is
Go to c-drive ==> Open app ==> Oracle ==> Product ==> 21c ==> SQL plus (Then it will connect to 21c version)
SQL Queries:
- Date: SQL>select sysdate from dual;
- Data files location: SQL>select name from v$datafile;
- To know the username: SQL>show user;
- To know the control file location: SQL>select name from v$controlfile;
- To get the field names in the view: SQL>desc v$log;
- To know the username in database: SQL>select username from dba_users:
Here sys and system are related to internal database operations
How to stop database services on windows:
Go to services ==> Select the relevant database service name ==> Right click and stop ==> After that in the status bar nothing is visible.
See Also: