First and foremost checkbox name should be in array format as shown in below code

because name with out array declaration cannot send multiple values.

html code

<input type="checkbox" name="hobbies[]" value="Reading Books">Reading Books	 
<input type="checkbox" name="hobbies[]" value="Playing Games">Playing Games 
<input type="checkbox" name="hobbies[]" value="Listening to music">Listening to music 

while getting the data using post method into php

Php code will like this

$hobbies = implode(",",$_POST['hobbies']);

here $_POST['hobbies'] will return array value and we cannot store array value into database.

The implode() function returns a string from the elements of an array.

by using any separator like ,/.#$% we can convert array into string