3.2 Simple Functions

function / argument

operates on an expression enclosed in parentheses, called an argument, and returns a value. Usually, the argument is a simple expression, such as a column name or fixed value. Some functions have several arguments, separated by commas, and a few have no arguments at all.

ABS()

Returns the absolute value.

LOWER()

returns lowercase

TRIM()

removes leading and trialing whitespace

SELECT TRIM(‘ HELLO ‘); — RETURNS ‘HELLO’

LTRIM()

Removes leading spaces from a string

RTRIM()

Removes trailing spaces from a string

HOUR(), MINUTE(), SECOND()

returns hour or minute or second from timestamp

SELECT HOUR(‘22:11:45’); — returns 22