Batch change all the prices

How can I Batch change all the prices to take of 10% without going through each individual item? I use easy populate, but that still means I have to calculate 10% off of each item pretty much manually.

Thanks in advance.

Back up your database and do the update through SQL, using phpMyAdmin or the SQL Patches facility under Tools.
So to decrease prices by 10%

update products set products_price = products_price * 0.9;
update products set products_price = round(products_price, 2);

Remember that if you use phpMyAdmin, you must include the prefix in the table name. So if the value of DB_PREFIX in includes/configure.php is 'zen_', you would use the commands

update zen_products ...

The advantage to using the SQL Patches facility is that you don't have to worry about this.

Thanks for the quick reply. I managed to calculate all of the prices quickly with a formula in Excel, then copy and paste into the correct column and used easy populate to update my product. But next time I'll try it through SQL (though it really intimidates me)

Make a backup, and then work fearlessly!

Some other tool i use for this is Apsona shopadmin which can import CSV data to zencart

Give it a try!