How I can solve this problem?

Question

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Please help
Create a query that will display the total number of employees and, of that total, the number of
employees hired in 1995, 1996, 1997, and 1998. Create appropriate column headings.

Answer 1

This can be achieved using SUM and CASE.
For example:
SELECT SUM (CASE WHEN hire_year='1991' then 1 else 0 end) "1991" , sum (Case WHEN HIRE_YEAR='1992' THEN 1 ELSE 0 END) "1992"
from emp ;