SELECT Statement — Complete Guide
SELECT Statement — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of MySQL Tutorial on Toolliyo Academy.
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MySQL Tutorial · Lesson 11 of 100
SELECT Statement
Basics → Advanced
Basics · 1 — SQL · ~6 min · MySQL — Queries & Clauses
What is this?
SELECT reads data from tables. You list columns (or *), pick a FROM table, and optionally filter or sort. It never changes data — only shows a result set.
Why should you care?
Every admin dashboard, export CSV, and API list endpoint starts as a SELECT. Wrong column list wastes bandwidth on mobile networks.
See it live — copy this example
Run in MySQL Workbench or the mysql CLI.
SELECT customer_id, full_name, city
FROM customers
WHERE city = 'Bengaluru';What happened?
- Only three columns return, not every column in the table.
- WHERE keeps Bengaluru customers.
- Result is a virtual table you can paginate or join further.
Practice next
- Seed customers in multiple cities.
- Run the SELECT and count rows.
- Add ORDER BY full_name and re-run.
- Select an expression: SELECT full_name, UPPER(city) AS city_upper FROM customers;
- Limit rows: add LIMIT 5 at the end.
Remember
SELECT projects columns from tables. Always name tables in FROM. Prefer explicit column lists in apps.
DataFlow support lookup
Support searches customers by city to bulk-email flood relief credits.
Outcome: Targeted SELECT avoids emailing entire user base.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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