# Introduction

Functions in SQL enable you to perform feats such as determining the sum of a column or converting all the characters of a string to

uppercase.

# Aggregate Functions

These functions are also referred to as group functions. They return a value based on

the values in a column.

## COUNT

The function COUNT returns the number of rows that satisfy the condition in the WHERE

clause.

## SUM

SUM returns the sum of all values in a column.

## AVG

The AVG function computes the average of a column.

## MAX

If you want to find the largest value in a column, use MAX.

## MIN

MIN returns the lowest member of a column.

## VARIANCE

VARIANCE produces the square of the standard deviation,

# Date and Time Functions

## ADD_MONTHS

This function adds a number of months to a specified date.

## LAST_DAY

LAST_DAY returns the last day of a specified month.

## MONTHS_BETWEEN

To know how many months fall between month x and month y.

# Arithmetic Functions

Many of the uses you have for the data you retrieve involve mathematics.

## ABS

The ABS function returns the absolute value of the number you point to.

# Character Functions

Many implementations of SQL provide functions to manipulate characters and strings of

characters.

# Conversion Functions

These three conversion functions provide a handy way of converting one type of data to

another.