How would it be more correct to get and write down the number of different values ​​from the database for the filter?

Question

PHP

Tell me, there is a query to the database, where we check 5 columns.

We need to get all the values ​​from them.

It is better to write them all into one array by means of push (into 5 different arrays for each), and after the column is checked, just check for a match in the array and get only 20 instead of 1000 values, where each of the 20 values ​​will have its own parameter about how many times it repeated in our array?

Or how it is done more correctly, maybe there is a less expensive solution for the server in sql itself?

The task is to get data for the filter.