SQL Fundamentals

Structured Query Language (SQL) is the standard language for interacting with Oracle Database. Oracle's implementation of SQL follows the ANSI/ISO SQL standard with powerful extensions. This lesson covers the essential SQL statements for querying, inserting, updating, and deleting data.

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SQL Statement Categories

Category	Statements	Purpose
DML (Data Manipulation Language)	SELECT, INSERT, UPDATE, DELETE, MERGE	Query and modify data
DDL (Data Definition Language)	CREATE, ALTER, DROP, TRUNCATE	Define database objects
DCL (Data Control Language)	GRANT, REVOKE	Control access privileges
TCL (Transaction Control Language)	COMMIT, ROLLBACK, SAVEPOINT	Manage transactions

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SELECT — Querying Data

Basic Syntax

SELECT column1, column2
FROM table_name
WHERE condition
ORDER BY column1;

Selecting All Columns

SELECT * FROM employees;

Column Aliases

SELECT first_name AS "First Name",
       salary * 12 AS annual_salary
FROM employees;

DISTINCT

SELECT DISTINCT department_id FROM employees;

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WHERE — Filtering Rows

Comparison Operators