我正在通過練習工作表提供問題和預期輸出。最後一個問題證明對我來說很難理解。任何人都可以請幫忙。初學者Oracle SQL計數函數多列
問題
創建一個查詢,顯示僱員總數和,即總的, 於2005年,2006年,2007年和2008年
預期輸出格式
僱用的員工人數Total 2005 2006 2007 2008
107 29 24 19 11
以下是我嘗試用單獨的查詢得到的結果
TO_CHAR(hire_date,'YYYY')
SELECT COUNT(employee_id) AS "Total"
FROM employees;
SELECT COUNT(employee_id) AS "2005"
FROM employees
WHERE TO_CHAR(hire_date,'YYYY') LIKE '2005' GROUP BY TO_CHAR(hire_date,'YYYY') ;
SELECT COUNT(employee_id) AS "2006"
FROM employees
WHERE TO_CHAR(hire_date,'YYYY') LIKE '2006' GROUP BY TO_CHAR(hire_date,'YYYY') ;
SELECT COUNT(employee_id) AS "2007"
FROM employees
WHERE TO_CHAR(hire_date,'YYYY') LIKE '2007' GROUP BY TO_CHAR(hire_date,'YYYY') ;
SELECT COUNT(employee_id) AS "2008"
FROM employees
WHERE TO_CHAR(hire_date,'YYYY') LIKE '2008' GROUP BY TO_CHAR(hire_date,'YYYY') ;
任何幫助產生的結果作爲一個查詢是非常感謝。
像這樣的東西應該工作:'SELECT COUNT(*)AS numEmpls,TO_CHAR(聘用日期, 'YYYY')AS的某些地方FROM員工GROUP BY TO_CHAR(聘用日期, 'YYYY')' –