28 Working with multiple

relegated to \"race music\" (the music industry code name for rhythm and

blues) outlets and was rarely heard by mainstream white audiences. In

1951, Cleveland, Ohio disc jockey Alan Freed would begin playing this type

of music for his white audience, and it is Freed who is credited with

coining the phrase \"rock and roll\" to describe the rollicking R&B music

that he brought to the airwaves." where genre="Rock"

I pulled this information off of Wikipedia (http://en.wikipedia.org/). You may find it easier

to go there and copy  some of this text out. Remember to watch out for quotes! You cannot

surround your text with the same kind of quotes that the text contains unless you backquote

the quotes in the text, as I've done with the history of rock above.

The final step is to replace the genres in the songs table with the genre ID we've just created.

First, create an unsigned integer column in songs called  genreID .

Since  we'll  be  searching  on  this  genreID,  you'll  want  to  create  a  standard  index  for  the

column as well.

Now, let's set the genre ID to the correct ID from the genres table. First, we text the where

we're going to use.

select song, artist, songs.genre, genres.genre, genres.id

from songs, genres

where songs.genre=genres.genre

If  that  shows  you  what  you'd  expect  to  see,  backup  your  data  (always  backup  your  data

before making a potentially data threatening change such as this!) and convert that select

into an update:

update songs, genres set genreID=genres.id where songs.genre=genres.genre

This may take a while! It has 7,000 records to update.

You should now be able to get genre information for any songs whose genre you've entered

information for. You'll only have to enter that information once for all songs of that genre;

and if you alter the name of the genre that alteration will follow through as long as the genre

ID stays the same.

select song, artist, description

from songs left join genres on songs.genreID=genres.id

where song like "%chain%"

order by artist

This  will  show  all  songs  whose  name  contains   chain ,  along  with  the  artist  and  the

description of the genre.