Basic SQL Syntax

Understanding SQL Syntax

SQL (Structured Query Language) follows a specific structure to perform operations such as retrieving, inserting, updating, and deleting data in a database. Knowing the correct syntax is essential to writing valid queries that Oracle can interpret.

General SQL Syntax

SELECT column1, column2
FROM table_name
WHERE condition;

Here's a breakdown:

• SELECT — specifies the columns you want to retrieve
• FROM — identifies the table to query
• WHERE — (optional) filters the results based on a condition

Example

SELECT first_name, last_name
FROM employees
WHERE department_id = 90;

This query fetches the first and last names of employees who work in department 90.

Practice Task

• Write a SQL query to retrieve all columns from the departments table.
• Try writing a query that selects job_id and salary from the employees table.
• What happens if you forget the FROM clause?