explanation given here is not fully correct-->"SELECT COUNT_BIG(ALL COlumn_2) and SELECT COUNT_BIG(column_2). COUNT_BIG(all column_2) will count all rows from the table (including duplicate & null rows). COUNT_BIG(DISTINCT column_2) will evaluate distinct non-null values.

:discuss:

because --->

"COUNT_BIG(all column_2) will count all rows from the table including duplicate & Excluding null rows).

and

COUNT_BIG(*) will count all rows from the table (including duplicate & null rows).