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simplifiedDB
Asked: 2013-11-19 05:29:54 +0800 CST

格式为 Varchar 时 MySQL 中的日期时间差异

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我在一个表中有两列：STOP和START，类型为varchar。

我想在两列之间有所区别，我正在使用： 

SELECT DATEDIFF(stop, start) AS difference from T1;

null由于不同的数据类型，它给了我。

为了测试，我还尝试了：

SELECT STR_TO_DATE('5/16/2011 20:14 PM', '%c %e %Y %H:%i:%s');

它也在给予null。

我该怎么办？我有n不同格式的数据和时间。

在此处输入图像描述

mysql mysql-5.5

1 个回答

  1. Best Answer

    您确实需要将所有日期和时间戳统一为一种格式，用于start和stop.

    举个例子，我将计算第一行的时间差。

    这是计算它的代码：

    SET @StartDT = 'Mon Jan 21, 21:07:47 IST 2013';
SET @StopDT  = 'Tue Jan 22, 07:59:58';
SET @YYYY_Start = SUBSTR(@StartDT,-4);
SET @MMM_Start  = RIGHT(LEFT(@StartDT,7),3);
SET @DD_Start   = RIGHT(LEFT(@StartDT,10),2);
SET @HMS_Start  = RIGHT(LEFT(@StartDT,20),8);
SET @YYYY_Stop  = SUBSTR(@StartDT,-4);
SET @MMM_Stop   = RIGHT(LEFT(@StopDT,7),3);
SET @DD_Stop    = RIGHT(LEFT(@StopDT,10),2);
SET @HMS_Stop   = RIGHT(LEFT(@StopDT,20),8);
SET @MM_Start   = RIGHT(LEFT((LOCATE(@MMM_Start,'JanFebMarAprMayJunJulAugSepOctNovDev')+2)/3+100,3),2);
SET @MM_Stop    = RIGHT(LEFT((LOCATE(@MMM_Stop,'JanFebMarAprMayJunJulAugSepOctNovDev')+2)/3+100,3),2);
SELECT @YYYY_Start,@YYYY_Stop,@MM_Start,@MM_Stop,@DD_Start,@DD_Stop,@HMS_Start,@HMS_Stop,@MM_Start,@MM_Stop;
SET @YYYMMDD_Start = CONCAT(@YYYY_Start,'-',@MM_Start,'-',@DD_Start);
SET @YYYMMDD_Stop  = CONCAT(@YYYY_Stop,'-',@MM_Stop,'-',@DD_Stop);
SET @TS_Start = CONCAT(@YYYMMDD_Start,' ',@HMS_Start);
SET @TS_Stop  = CONCAT(@YYYMMDD_Stop,' ',@HMS_Stop);
SET @TimeDiffSec = UNIX_TIMESTAMP(@TS_Stop) - UNIX_TIMESTAMP(@TS_Start); 
SET @TimeDiff = SEC_TO_TIME(@TimeDiffSec); 
SELECT @TS_Start,@TS_Stop,@TimeDiffSec,@TimeDiff;

    准备好看到不同了吗？这里是：

    mysql> SET @StartDT = 'Mon Jan 21, 21:07:47 IST 2013';
Query OK, 0 rows affected (0.00 sec)

mysql> SET @StopDT  = 'Tue Jan 22, 07:59:58';
Query OK, 0 rows affected (0.00 sec)

mysql> SET @YYYY_Start = SUBSTR(@StartDT,-4);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @MMM_Start  = RIGHT(LEFT(@StartDT,7),3);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @DD_Start   = RIGHT(LEFT(@StartDT,10),2);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @HMS_Start  = RIGHT(LEFT(@StartDT,20),8);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @YYYY_Stop  = SUBSTR(@StartDT,-4);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @MMM_Stop   = RIGHT(LEFT(@StopDT,7),3);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @DD_Stop    = RIGHT(LEFT(@StopDT,10),2);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @HMS_Stop   = RIGHT(LEFT(@StopDT,20),8);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @MM_Start   = RIGHT(LEFT((LOCATE(@MMM_Start,'JanFebMarAprMayJunJulAugSepOctNovDev')+2)/3+100,3),2);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @MM_Stop    = RIGHT(LEFT((LOCATE(@MMM_Stop,'JanFebMarAprMayJunJulAugSepOctNovDev')+2)/3+100,3),2);
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT @YYYY_Start,@YYYY_Stop,@MM_Start,@MM_Stop,@DD_Start,@DD_Stop,@HMS_Start,@HMS_Stop,@MM_Start,@MM_Stop;
+-------------+------------+-----------+----------+-----------+----------+------------+-----------+-----------+----------+
| @YYYY_Start | @YYYY_Stop | @MM_Start | @MM_Stop | @DD_Start | @DD_Stop | @HMS_Start | @HMS_Stop | @MM_Start | @MM_Stop |
+-------------+------------+-----------+----------+-----------+----------+------------+-----------+-----------+----------+
| 2013        | 2013       | 01        | 01       | 21        | 22       | 21:07:47   | 07:59:58  | 01        | 01       |
+-------------+------------+-----------+----------+-----------+----------+------------+-----------+-----------+----------+
1 row in set (0.00 sec)

mysql> SET @YYYMMDD_Start = CONCAT(@YYYY_Start,'-',@MM_Start,'-',@DD_Start);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @YYYMMDD_Stop  = CONCAT(@YYYY_Stop,'-',@MM_Stop,'-',@DD_Stop);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @TS_Start = CONCAT(@YYYMMDD_Start,' ',@HMS_Start);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @TS_Stop  = CONCAT(@YYYMMDD_Stop,' ',@HMS_Stop);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @TimeDiffSec = UNIX_TIMESTAMP(@TS_Stop) - UNIX_TIMESTAMP(@TS_Start);
Query OK, 0 rows affected (0.00 sec)

mysql> SET @TimeDiff = SEC_TO_TIME(@TimeDiffSec);
Query OK, 0 rows affected (0.00 sec)

    最终答案

    mysql> SELECT @TS_Start,@TS_Stop,@TimeDiffSec,@TimeDiff;
+---------------------+---------------------+--------------+-----------+
| @TS_Start           | @TS_Stop            | @TimeDiffSec | @TimeDiff |
+---------------------+---------------------+--------------+-----------+
| 2013-01-21 21:07:47 | 2013-01-22 07:59:58 |        39131 | 10:52:11  |
+---------------------+---------------------+--------------+-----------+
1 row in set (0.00 sec)

    尽管这是正确的，但为所有行编写这种复杂的方法是不合逻辑的，尤其是因为某些行具有不同的格式。

    因此，将start和stop列转换为DATETIME或符合您的最大利益TIMESTAMP

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