Concurrency Problem? update together in the same time

[.hack//GU 0]

I have a problem in PHP.When more than one client update something in database, they won't work.so, how do I make out for it?example:at the same time, in real-time chatboard, 2 persons click CHAT, what can I do so that both of them actually chat?or at bidding website, when 2 persons bid at same time, how could I do that?thanks for answer.

[urtrivedi 0]

Actually You can build Transactions before update or inserting data into database. also don't work with out proper primary and foreign keys in you tables.
Try to use autogenerate option for primary keys.

I suppose you are using mysql database,
I dont know about mysql transactions, but I use oracle 10g.

If I have to execute set of 2 query in the manner that 2 should succeed or no query should execute.

$query1="some insert";$statement1 = oci_parse($connection, $query1);if ((oci_execute($statement1,OCI_DEFAULT))){[indent]	 $query2="some more insert";	 $statement2 = oci_parse($connection, $query2);	 if ((oci_execute($statement2,OCI_DEFAULT)))	[indent]		   oci_commit($connection));   [/indent]	 	 else[indent]			  oci_rollback($connection));  [/indent][/indent]}else{			  oci_rollback($connection))  ;}

You please specify what problem exactly you are facing. Why you feel that you data is not concurrent.

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Edited May 26, 2008 by rvalkass (see edit history)