[![enter image description here](https://i.stack.imgur.com/bRQ1s.png)](https://i.stack.imgur.com/bRQ1s.png)

Hi all, i have this dataset which is the sales of some products. Date field is the date of sale, Brand the Brand of the product, Channel is the Channel that the product is sold and Sales is the price that the product is sold.

I need to show for every month, channel and brand the total price (Sales) and the total price of previous month in sql.
I can retrieve the total price of the current month with a query like this

```
SELECT TO_CHAR(DATE,'MONTH'), BRAND CHANNEL, SUM(SALES) FROM SAELS
GROUP BY TO_CHAR(DATE,'MONTH'), BRAND CHANNEL

```

But how i can take the total sales of the previous month?