Which SQL statement is faster? (HAVING vs. WHERE…)

Question

SELECT NR_DZIALU, COUNT (NR_DZIALU) AS LICZ_PRAC_DZIALU
    FROM  PRACOWNICY
    GROUP BY NR_DZIALU
    HAVING NR_DZIALU = 30

or

SE         


        

Answer 1

"Having" is slower if we compare with large amount of data because it works on group of records and "WHERE" works on number of rows..

"Where" restricts results before bringing all rows and 'Having" restricts results after bringing all the rows