SQL dialects teaser

This track teaches portable ANSI SQL, but real engines differ in types, functions, and DDL. When you deploy, pick a dialect and dive into its track: MySQL for many LAMP/WordPress stacks, PostgreSQL for advanced types and JSON, SQLite for embedded and learning.

Common differences

• Auto-increment — SERIAL, AUTO_INCREMENT, INTEGER PRIMARY KEY
• Boolean — native BOOL vs INTEGER 0/1
• String ops — || vs CONCAT
• Date functions — date_trunc (Postgres) vs DATE_FORMAT (MySQL)
• Full outer join — Postgres yes; MySQL historically no

Same query, different engines

-- Portable core
SELECT id, name FROM customers WHERE id = 1;

-- Postgres-specific (see /postgresql/intro)
-- SELECT * FROM orders WHERE ordered_at >= NOW() - INTERVAL '7 days';

-- MySQL-specific (see /mysql/intro)
-- SELECT * FROM orders WHERE ordered_at >= DATE_SUB(NOW(), INTERVAL 7 DAY);

Learn concepts here; learn engine quirks in dialect tracks.

Choosing a database

Postgres for rich SQL and extensions; MySQL/MariaDB for widespread hosting; SQLite for local dev and mobile; cloud warehouses for analytics. App frameworks often abstract the driver—still test on production dialect.

Important interview questions and answers

1. Q: One ANSI SQL benefit?
   A: Skills transfer—SELECT/JOIN/GROUP BY core is shared across engines.
2. Q: When read dialect docs?
   A: Before using engine-specific DDL, functions, or performance features in production.

Self-check

1. Which track covers PostgreSQL-specific features?
2. Name one syntax difference between MySQL and Postgres dates.

Tip: Continue on PostgreSQL or MySQL when you pick a production engine.