Here's a possible SQL query:

```
SELECT DISTINCT StockID
FROM StockPrices current
WHERE EXISTS (
  SELECT 1
  FROM StockPrices past
  WHERE past.StockID = current.StockID
    AND past.Date >= DATEADD(month, -1, current.Date)
    AND past.Date < current.Date
    AND current.Price >= past.Price * 1.2
)
```

This query uses a correlated subquery to test for the existence of a matching row in the past month whose price is at most 80% of the current row's price (which is equivalent to a 20% increase). The `DISTINCT` keyword removes duplicates in case there are multiple such rows for a given stock. The `DATEADD` function is used to calculate the date one month before the current date. Note that the query assumes that the `Date` column is of a date or datetime data type.
Data una tabella dei prezzi giornalieri delle azioni con le colonne StockID, Date e Price, scrivere una query SQL per trovare le azioni i cui prezzi sono aumentati di almeno il 20% nell'ultimo mese.