Problem

Given a table of data with two columns, write a SQL query to find the number of rows where the value in the second column is greater than the value in the first column.
Input:
| Column 1 | Column 2 |
|----------|----------|
| 1        | 3        |
| 2        | 4        |
| 3        | 2        |
| 4        | 1        |
Output:
3

Solution

SELECT COUNT(*)
FROM table
WHERE column2 > column1;

/*

The above solution is optimal because it uses a single query to find the number of rows where the value in the second column is greater than the value in the first column.

*/