How to find duplicate count among several columns?

Question

Here is a sample table that mimics my scenario:

COL_1   COL_2   COL_3   COL_4   LAST_COL
A       P       X       NY      10
A       P       X       NY      11
A          


        

Answer 1

The GROUP BY is what you want here. For example:

SELECT COL_1, COL_2, COL_3, COL_4, COUNT(*)
FROM my_table
GROUP BY COL_1, COL_2, COL_3, COL_4