[英]My Sql merging rows
我如何查询具有相同日期的合并行并摆脱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
对此
Date | Long | Short
2006-07-06 | t1 | t2
2006-07-05 | t1 | t2
2006-07-04 | t1 | t2
2006-07-03 | t1 | t2
获取指定结果集的一种方法是使用GROUP BY和聚合函数:
SELECT t.Date
, MAX(t.Long) AS `Long`
, MAX(t.Short) AS `Short`
FROM mytable t
GROUP
BY t.Date
SELECT `date`, MAX(`long`) `long`, MAX(short) short
FROM yourtable
GROUP BY `date`
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