let vUpdateDate=peek('Date_updated',-1,'sort_sales');

[d_koti24]

what is the meaning of the above expr

[#2]

It finds the last record read in your dataset from column Date_updated in table sort_sales

Note: if it was 0 it was the first record

[#3]

peek('Date_updated',-1,'sort_sales');

returns the last row from the field Date_updated in the table sort_sales.

your assigning the result to vUpdatedate variable.

[tresesco]

There is table named 'sort_sales' which has a field named 'Date_updated'. If the table has already been loaded into qv, then this expression would store the last field ('Date_updated') value read into the variable called vUpdateDate.

Read Peek(), for details.