hi,

I have two tables that are related, ie I created them with;

create table cm_message (
msgid varchar(40) not null primary key,
location varchar(240),
ts timestamp default 'now' not null,
lastsent timestamp
);

create table cm_data (
pkey integer not null primary key,
subdata varchar(255),
msgid varchar(40),
foreign key (msgid) references cm_message(msgid)
);

basically for each entry in cm_message there can be several cm_data entries and they're linked using the msgid fields.

I'm trying to write a purge script that will delete entries (in cm_message and cm_data) that have a cm_message.ts timestamp older than n hours. Can I do a 'delete from ... where cm_message.ts > n' which does some kind of union between the two tables and delete entries from both tables at one stroke?

At the moment I'm looking at selecting all old entries from cm_message and deleting all in cm_data for each msgid, but there must be a more efficient way of using the relational stuff...

thanks,
nik

Use the ON DELETE CASCADE option:

Code:

...foreign key (msgid) references cm_message(msgid) ON DELETE CASCADE

which database system is this? because i don't know of any that will support this --

thanks LKBrwn_DBA.

rudy, the database is firebird - I think it also accepts TODAY, TOMORROW and YESTERDAY which is nice and handy...

nik

wow, ya learn sumpin new every day

thanks nik

Hi,

Does it work on a MySQL database?

//M

the ON DELETE CASCADE? only for InnoDB tables