Oracle Database is a powerful Relational Database Management System (RDBMS) developed by Oracle Corporation.It is widely used to store, organize, retrieve, manipulate, and secure large volumes of structured data.Oracle supports SQL (Structured Query Language) for working with data and PL/SQL (Procedural Language/SQL) for developing database-side programs.
Oracle is commonly used in enterprise applications because it provides:
- High performance
- Scalability
- Security
- Transaction management
- Backup and recovery
- Concurrency control
- High availability
- Data integrity
- Support for very large databases
- Integration with Java, Python, .NET and other technologies
Oracle as an RDBMS
Oracle follows the relational database model. Data is organized into tables consisting of:
| Concept | Description |
|---|---|
| Database | Collection of related data |
| Table | Stores data in rows and columns |
| Row | Represents one record |
| Column | Represents an attribute |
| Primary Key | Uniquely identifies a row |
| Foreign Key | Establishes relationship between tables |
| Constraint | Enforces data integrity |
Oracle uses SQL to interact with the database.
| Command | Description |
|---|---|
CREATE |
Creates a new database object. |
ALTER |
Modifies an existing database object. |
DROP |
Deletes a database object. |
TRUNCATE |
Removes all rows from a table. |
RENAME |
Renames a database object. |
INSERT |
Adds new records to a table. |
UPDATE |
Modifies existing records. |
DELETE |
Removes records from a table. |
SELECT |
Retrieves data from a table. |
WHERE |
Filters records based on a condition. |
DISTINCT |
Removes duplicate values from the result. |
ORDER BY |
Sorts the query result. |
GROUP BY |
Groups rows with similar values. |
HAVING |
Filters grouped records. |
JOIN |
Combines data from multiple tables. |
UNION |
Combines results of two queries and removes duplicates. |
UNION ALL |
Combines results of two queries including duplicates. |
INTERSECT |
Returns common records from two queries. |
MINUS |
Returns records present in the first query but not the second. |
COMMIT |
Permanently saves transaction changes. |
ROLLBACK |
Undoes uncommitted transaction changes. |
SAVEPOINT |
Creates a point for partial rollback. |
GRANT |
Provides privileges to a user. |
REVOKE |
Removes privileges from a user. |
Important Oracle Data Types
Some commonly used Oracle data types are:
| Data Type | Purpose |
|---|---|
NUMBER |
Numeric values |
VARCHAR2 |
Variable-length text |
CHAR |
Fixed-length text |
DATE |
Date and time |
TIMESTAMP |
Precise date/time |
CLOB |
Large character data |
BLOB |
Binary data |
Oracle Schema and Database Objects
Important Oracle objects include
- Tables – Store data
- Views – Virtual tables based on queries
- Indexes – Improve query performance
- Sequences – Generate numeric values
- Synonyms – Alternative names for objects
- Procedures – Store reusable database programs
- Functions – Return values
- Triggers – Automatically execute in response to events
- Packages – Group related PL/SQL components
The same above referred as schema elements.
Oracle Tools
Common tools used with Oracle include:
- Oracle SQL Developer
- SQL*Plus
- Oracle Enterprise Manager
- Oracle Database tools
- Oracle Cloud Infrastructure (OCI)
For beginners, Oracle SQL Developer provides a convenient graphical environment for writing SQL, managing tables, and exploring database objects.
For oracle database downloads refer
https://www.oracle.com/in/database/technologies/oracle-database-software-downloads.html