比较两个PHP报表之间的差异

Question

I have a PHP script which currently draws out information from a MySQL database where one of the columns values are set as 'on - ie table(product) column 'on_amazon' - VALUE = 'on'.

Table : Product
Column : on_amazon
Value : 'on' 

This report brings through all products that are currently marked as 'on' and the specified rows.

I need to be able to run this report each day and show any differences between the last report and the current one. This would reflect if there are an quantity differences for example between today and the previous day.

I was thinking I should create a new table, dump the data inside, compare each new day with the previous table, overwrite the previous table with the new data. Rinse and repeat.

Are there any better suggestions to this approach?

Thanks,

Answer 1

Assuming you basically want to see how many products were sold today I would simply add columns to the product table, one for total products sold on a day "sold_today" and a last transaction date column "tran_date". Upon the update of the table's quantity column, for instance when 1 product gets sold, I would do something like this:

update product set quantity = quantity - 1, 
    case when datediff(tran_date,curdate()) >= 1
       then sold_today = 1
       else sold_today = sold_today + 1
    end,
    tran_date = curdate()
where product_id = product_to_update;

The accuracy of the above statement (and also the option you mentioned) will be highly dependable on the time you run the statement because the data will get overwritten.

IMHO, a better solution would be to create a detailed transaction table specifically to store what product was sold when and then you just have to count the number of records for a specific date. This would also enable you to run statistical reports for any day.