Question 1: is there a good explination online of how to use the JOIN
function in mysql? I've looked at the documentation:

http://www.mysql.com/doc/J/O/JOIN.html

but it's to confusing. It doesn't exactly what you are joining or why you
might want to do that ... I think JOIN is what I need, here is the problem:




So I have some tables:


create table maps
(
rowid INT(10) AUTO_INCREMENT PRIMARY KEY NOT NULL
);

create table locations
(
map INT(10),  #map rowid
rowid INT(10) AUTO_INCREMENT PRIMARY KEY NOT NULL
);

create table notes
(
location INT(10), ## location rowid
rowid INT(10) AUTO_INCREMENT PRIMARY KEY NOT NULL
);



Each map has many locations and each location has many notes ...

I want to delete the map, all of it's locations and all of the locations
notes.

clearing the maps and locations is easy:

$sql = "DELETE FROM maps WHERE (rowid='$mapid')";
$result = mysql_query($sql);

$sql = "DELETE FROM locations WHERE (map='$mapid')";
$result = mysql_query($sql);


but how to get rid of those notes?


I'm thinking of sending all of the location rowid(s) to an array then using
that array to delete the notes ... but I think this JOIN thing might let me
do it all with one query.

Can any of you kind folks help me here?


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