如何獲得查詢結果的最大日

Question

我有我喜歡的查詢結果是：基於上述查詢結果

empName project leavedate 
abc  pjt1 10/10/2013 
abc  pjt1 10/12/2013 
abc  pjt2 10/10/2011 

我想對每個項目的最後日期上，他已經放假了。它不是查詢結果。

Answer 1

SELECT MAX(leavedate) FROM my_table_; 

http://www.w3schools.com/sql/sql_func_max.asp

Answer 2

SELECT t1.empName, t1.project, t1.leavedate 
FROM <yourTable> t1 
WHERE NOT EXISTS (SELECT * FROM <yourTable> t2 
        WHERE t1.project = t2.project AND t2.leavedate > t1.leavedate) 

Answer 3

這給一個鏡頭：

SELECT empName, project, MAX(leavedate) 
    FROM mytable 
GROUP BY project;