These instructions are based on my own setup where the database is on a localhost on my own computer. Situations may be slightly different if the database is hosted elsewhere.
For this example we're looking at backing up a database named 'joomla15'.
IMPORTANT NOTE : Within the SQL structure it is possible to select databases, tables, or individual fields for editing, backup, deletion etc. These work instructions however are only concerned with backing up the WHOLE database. Unless you know what you're doing I would suggest you don't deviate from them as you can really screw things royally.