How to detect and remove a column that contains only null values?

Question

In my table table1 there are 6 columns Locations,a,b,c,d,e.

Locations [a]   [b]   [c]  [d]   [e]

[1]       10.00 Null  Null 20.00 Null

[2]         


        

Answer 1

SELECT * FROM table1 WHERE c IS NOT NULL  -- or also SELECT COUNT(*)

To detect if indeed this column has no values at all.

ALTER TABLE table1 DROP COLUMN c

is the query to remove the column if it is deemed desirable.