How to select specific columns

List columns

Separate requested columns with commas. The result follows the order in the SELECT list.

SELECT title, level, duration_minutes
FROM courses;

Prefer explicit lists

Named columns communicate intent, transfer less unnecessary data, and keep result shapes stable when a table later gains a column.

Calculate values

A select list can contain expressions as well as stored columns.

SELECT title, duration_minutes / 60.0 AS duration_hours
FROM courses;

Qualify when needed

Prefix a column with its table name or alias when several source tables have a column with the same name.

SELECT courses.title, courses.level
FROM courses;