SELECT usage and examples

Overview

SELECT defines the columns or expressions returned by a query. Listing only the required columns keeps the result shape stable and avoids unnecessary data transfer; calculated expressions should use clear aliases. Use SELECT * only when every column is genuinely needed.

Basic syntax

SELECT name, amount FROM orders;

Examples

SELECT example

Read only name and amount from orders and compare the returned columns with the SELECT list.

Sample table

Table：orders

orders
name	amount
Alice	1200
Bob	900
Cindy	1500
David	700

Run result

result
name	amount
Alice	1200
Bob	900
Cindy	1500
David	700

Common issues

Does SELECT always need FROM?

Usually yes when querying table data, but MySQL can also select expressions directly, such as SELECT 1 + 1.

Why avoid SELECT * in regular queries?

SELECT * returns every column, which can make results unclear and increase transfer and reading cost as tables grow.

Can SELECT contain calculated expressions?

Yes. For example, amount * 1.13 AS amount_with_tax. Use a clear alias for readability.

Keep reading

WHERE DISTINCT ORDER BY LIMIT LIKE BETWEEN OFFSET IS NULL

SELECT