Question

我正在努力处理Mysql代码，而且不知道如何解决此问题。我有两列具有时间值的列，这些列是我在Mysql Query结果中按desc排序的。

我需要找出第二行StateEndTime和第一行StateStarTtime nd之间的差异，然后将其显示在新的行/列中。决赛桌应该像这样：

ID          Type         StateStarTtime    StateEndTime   Min Difference

xxx         YYY          03:57             03:59          00:02
xxx         ZZZ          03:53             03:55          00:04
xxx         ZZZ          03:46             03:49

Answer 1

假设ID是一个自动递增列，则可以在MySQL中通过自连接技术来实现：

 SELECT 
  t1.ID,
  t1.Type,
  t1.StateStartTime,
  t1.StateEndTime
  (t1.StateStartTime - t2.StateEndTime) AS Min_Diff
 FROM
 Table1 t1
    INNER JOIN
 Table1 t2 ON t2.id = t1.id + 1

Answer 2

这是您要做什么吗？

  mysql_query("SELECT *, `StateEndTime`-`StateStarTtime` AS `Min Difference` 
  FROM `TableName`");

Answer 3

这可以在带有CTE和/或ROW_NUM函数的MYSQL 8中简化，但这将在大多数版本中为您提供所需的解决方案。

我还按照您的时间投放了示例，因为它们没有正确的格式，在您的实际数据中可能并非如此。

SET @row_number_a = 0;
SET @row_number_b = -1;

SELECT a.id, a.type, a.start, a.end, TIMEDIFF(CAST(a.start AS TIME), CAST(b.end AS TIME)) AS DIFF  
FROM
(SELECT (@row_number_a:=@row_number_a + 1) AS num, id, type, start, end
FROM tbl) a

LEFT JOIN (
SELECT (@row_number_b:=@row_number_b + 1) AS num, id, type, start, end
FROM tbl
) b
ON a.num = b.num

结果：

"id"    "type"  "start" "end"   "DIFF"
"xxx"   "YYY"   "03:57" "03:59" "00:02:00"
"xxx"   "ZZZ"   "03:53" "03:55" "00:04:00"
"xxx"   "ZZZ"   "03:46" "03:49" \N

MySQL查询用第二行的第二列减去第一行的第一列

3 个答案: