我的SQL合並行

Question

我如何查詢具有相同日期的合並行並擺脫null

Date       | Long | Short
2006-07-06 | t1   |
2006-07-06 |      | t2
2006-07-05 | t1   | 
2006-07-05 |      | t2
2006-07-04 | t1   |
2006-07-04 |      | t2
2006-07-03 | t1   | 
2006-07-03 |      | t2

對此

Date       | Long | Short
2006-07-06 | t1   | t2
2006-07-05 | t1   | t2
2006-07-04 | t1   | t2
2006-07-03 | t1   | t2

Answer 1

獲取指定結果集的一種方法是使用GROUP BY和聚合函數：

SELECT t.Date
     , MAX(t.Long) AS `Long`
     , MAX(t.Short) AS `Short`
  FROM mytable t
 GROUP
    BY t.Date

Answer 2

SELECT `date`, MAX(`long`) `long`, MAX(short) short
FROM yourtable
GROUP BY `date`