Используя схему OracleHR с ее таблицами следует написать запрос на языке SQL, который позволит получить количество сотрудников имена которых начинается с одной и той же буквы. Сортировать по количеству. Показывать только те, где количество больше 1 из таблицы Employees.

SELECT SUBSTR (first_name, 1, 1) first_char, COUNT (*) FROM employees GROUP BY SUBSTR (first_name, 1, 1) HAVING COUNT (*) < 1 ORDER BY 2 DESC;
SELECT SUBSTR (first_name, 1, 1) first_char, COUNT (*) FROM employees GROUP BY SUBSTR (first_name, 1, 1) HAVING COUNT (*) < 1 ORDER BY 2 DESC;
SELECT SUBSTR (first_name, 1, 1) first_char, COUNT (*) FROM employees GROUP BY SUBSTR (first_name, 1, 1) HAVING COUNT (*) > 1 ORDER BY 2 DESC;
SELECT SUBSTR (first_name, 1, 1) first_char, COUNT (*) FROM employees GROUP BY SUBSTR (first_name, 1, 1) HAVING COUNT (*) >= 1 ORDER BY 2 DESC;
SELECT SUBSTR (first_name, 1, 1) first_char, COUNT (*) FROM employees GROUP BY SUBSTRINGER (first_name, 1, 1) HAVING COUNT (*) > 1 ORDER BY 2;
SELECT SUBSTR (first_name, 1, 1) first_char, COUNT (*) FROM employees GROUPED BY SUBSTR (first_name, 1, 1) HAVING COUNT (*) > 1 ORDER BY 2 DESCRIPTION;
SELECT SUBSTR (first_name, 1, 1) first_char, COUNTER (*) FROM employees GROUP BY SUBSTR (first_name, 1, 1) HAVING COUNT (*) < 1 ORDER BY 2 DESC;
SELECT SUBSTR (first_name, 1, 1) first_char, DISCOUNTER (*) FROM employees GROUP BY SUBSTR (first_name, 1, 1) HAVING COUNT (*) > 1 ORDER BY 2 DESC;

Для просмотра статистики ответов нужно войти.