One the left I have pages as months in one Year.
I want to have one widget page (table or chart) that will group sums from all months. I want to see only one column: CENA [NETTO] like this:
Take a look at the summary tables feature. You should be able to create a Summary Table that just groups by date (or just a month) and sums all amounts in the NETTO column.
I’ve created a simple document (link) that illustrates how this can be done.
You probably have a Date column in List przewozowy table, so first you need to add another column that will extract a month from it. This is needed as we need to group this table using some common value. I like to use EOMONTH method, which returns the last day of a month from a particular date. Add a new column called Month with a formula EOMONTH($Date,0). You can use a different formating for this column, to just show the month part, for example YYYY-MMMM
Create a summary table, that groups the List przewozowy table by this column:
You should have a new table, that automatically groups and sums all NUMERIC columns based on the month. Of course, you can remove or hide all other columns that you don’t need: