بسم الله الرحمن الرحيم

SELECT ROUND(MAX(salary),0) "Maximum",
ROUND(MIN(salary),0) "Minimum",
ROUND(SUM(salary),0) "Sum",
ROUND(AVG(salary),0) "Average"
FROM employees;

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SELECT job_id, ROUND(MAX(salary),0) "Maximum",
ROUND(MIN(salary),0) "Minimum",
ROUND(SUM(salary),0) "Sum",
ROUND(AVG(salary),0) "Average"
FROM employees
GROUP BY job_id;

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SELECT job_id, COUNT(*)
FROM employees
GROUP BY job_id;

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SELECT job_id, COUNT(*)
FROM employees
WHERE job_id = '&job_title'
GROUP BY job_id;

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SELECT COUNT(DISTINCT manager_id) "Number of Managers"
FROM employees;

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SELECT MAX(salary) - MIN(salary) DIFFERENCE
FROM employees;

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SELECT manager_id, MIN(salary)
FROM employees
WHERE manager_id IS NOT NULL
GROUP BY manager_id
HAVING MIN(salary) > 6000
ORDER BY MIN(salary) DESC;

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SELECT COUNT(*) total,
SUM(DECODE(TO_CHAR(hire_date, 'YYYY'),1995,1,0))"1995",
SUM(DECODE(TO_CHAR(hire_date, 'YYYY'),1996,1,0))"1996",
SUM(DECODE(TO_CHAR(hire_date, 'YYYY'),1997,1,0))"1997",
SUM(DECODE(TO_CHAR(hire_date, 'YYYY'),1998,1,0))"1998"
FROM employees;

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SELECT job_id "Job",
SUM(DECODE(department_id , 20, salary)) "Dept 20",
SUM(DECODE(department_id , 50, salary)) "Dept 50",
SUM(DECODE(department_id , 80, salary)) "Dept 80",
SUM(DECODE(department_id , 90, salary)) "Dept 90",
SUM(salary) "Total"
FROM employees
GROUP BY job_id;

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و الله المستعان

استاذنا المبدع سامح ..

جزاك الله خيرا و وفقك لكل خير ..

أبشرك بأني حليت الواجب سابقا ( يعني لم أغش )..

و الحمد لله تمام .. ما عدا آخر سؤالين لم أستطع حلهما ..

و لما قرأت الإجابة .. عرفت فعلا أنك استاذ مبدع ..

بالتوفيق يا محمد ...

أشكرك أستاذ sameh bakkar على هذا الجهد

المبذول والعطاء المتواصل وفقك الله.