At 12:08 +1100 3/5/03, Daniel Kasak wrote:
Paul DuBois wrote:
That is, you're making an assumption that cannot necessarily be made.
If you can guarantee that the web script will establish a new connection,
and the connection will terminate when the script ends, you can indeed
do what you describe above.
But you *cannot* do that if you're running your script in an environment
that uses persistent connections that may be used by successive instances
of the script. PHP persistent connections fall into this class, for
example. Several requests might be served by the same instance of the
web server process, and you don't know that one request won't be getting
the connection used by a previous request. In that case, the connection
won't have closed, and the TEMPORARY table won't have disappeared.
You can guard against this by issuing this query before creating the
TEMPORARY table:
DROP TABLE IF EXISTS tbl_name
In this case I would actually use unique table names.
If you have a web server that is set up to use persistant database
connections and there is a chance that 2 clients may run the same
script in the same connection, then dropping the tmp table isn't
going to solve all of your problems. You can't have the 2nd instance
of the script screwing with the 1st. If you have some form of unique
identifier, then append it to the table name. Otherwise consider
creating your own (and testing for it's existance before using it)
and appending it to the table name.
Dropping the table before attempting to use it eliminates any need to
come up with a unique name.
Two clients *cannot* run the same script at the same time, *unless* they
are being executed by different web server processes. In that case, they'll
be using different connections, and a temporary table created by one
connection cannot be seen by the other connection.
--
Daniel Kasak
IT Developer
* NUS Consulting Group*
Level 18, 168 Walker Street
North Sydney, NSW, Australia 2060
T: (+61) 2 9922-7676 / F: (+61) 2 9922 7989
email: [EMAIL PROTECTED]
website: www.nusconsulting.com
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