Question

I was wondering as to
how do I ensure multiple queries are executed
or rollback to original state if one of the query fail

For example:

$qry1 = insert into table 1 (coloum1,coloum2) values(a,b);
$qry2 = update table 2 set coloum3 = coloum3 - 1;

Similarily there are about 4 queries which ae to be executed.
in a scenario like:

1. inserting item sales to items table.
2. updating the stock of all those items in the stock balance table.
3. inseting the journal entries to the journal tables.
   and so on.

Basically either all the queries should run or none of them runs.

Answer 1

Transactions are the way to go. http://www.devshed.com/c/a/MySQL/Using-Transactions-In-MySQL-Part-1/