在sqlite中转换12小时到24小时的时间格式 [英] Converting 12 hour to 24 hour time format in sqlite
问题描述
<$ p $ CREATE TABLE rawdata(
timestamp text,
value REAL
);
.separator,
.import'〜/文件路径/ rawdata.txt'rawdata
'rawdata.txt'文件如下所示:
2012/4/14 3:50:09 PM,24.7
2012/4/14 3:51:09,24.2
2012/4/14 3:52:09,99.3
然后在命令提示符下使用以下命令创建一个名为RAWDATA.db的数据库,并在其中包含rawdata表:
sqlite3 RAWDATA.db< 〜/ path to scripts / importscript.sql
导入完成后的表格看起来像这样:
时间戳记值
2012/4/14 3:50:09 24.7
4/14 / 2012 3:51:09 PM 24.2
2012/4/14 3:52:09 PM 99.3
但我希望它看起来像这样
时间戳记值
2012/4/14 15:50 :09 24.7
2012/4/14 15:51:09 24.2
2012/4/14 15:52:09 99.3
如何将此时间戳列转换为24小时制?
为了使用SQLite日期/时间函数并允许日期比较(和排序),日期应该存储在 YYYY-MM-DD HH:MM-SS
/ p> 所以,我的答案会解决你的问题和这个日期转换:
pre $ UPDATE rawdata SET timestamp =(SELECT DATETIME(SUBSTR(timestamp,s2 + 1,4)|| '-01-01',
SUBSTR(timestamp,1,s1 -1)||'months','-1 months',
SUBSTR(timestamp,s1 + 1,s2-s1-1 )||'days','-1 days',
SUBSTR(timestamp,s3 + 1,s4-s3-1)||'hours',
SUBSTR(timestamp,s4 + 1,s5 SUBSTR(时间戳,s5 + 1,s6-s5-1)||'秒',
SUBSTR时间戳(时间戳,s3 + 1,s4 --s3-1)= '12'THEN'-12小时'ELSE'0小时'END,
SUBSTR时间(时间戳,s6 + 1)像'PM'那么'+12小时'其他'0小时'END
)
FROM(
SELECT *,
INSTR(SUBSTR(timestamp,s1 + 1),'/')+ s1 AS s2,
INSTR SUBSTR(timestamp,s4 + 1),':')+ s4 AS s5,
INSTR(SUBSTR(timestamp,s3 + 1),'')+ s3 AS s6
FROM(
SELECT timestamp,
INSTR(timestamp,'/')AS s1,
INSTR(timestamp,'')AS s3,
INSTR(timestamp,':')AS s4
)
));
这个可怕的块得到所有分隔符的位置,从组件中重建日期并处理 PM
。注意 1 ... 11AM => +0
和 1 ... 11PM => +12
,但是 12AM => -12
和 12PM => +0
!
在 SQL小提琴。
Say I have a script named 'importscript.sql' to create a table and populate it from a text file named 'rawdata.txt' like so:
CREATE TABLE rawdata (
timestamp text,
value REAL
);
.separator ,
.import '~/path of the file/rawdata.txt' rawdata
The 'rawdata.txt' file looks like this:
4/14/2012 3:50:09 PM,24.7
4/14/2012 3:51:09 PM,24.2
4/14/2012 3:52:09 PM,99.3
Then creating a database named RAWDATA.db with the rawdata table in it in the command prompt using:
sqlite3 RAWDATA.db < ~/path to the script/importscript.sql
The table when the import is complete will look like this:
timestamp value
4/14/2012 3:50:09 PM 24.7
4/14/2012 3:51:09 PM 24.2
4/14/2012 3:52:09 PM 99.3
But I want it to look like this
timestamp value
4/14/2012 15:50:09 24.7
4/14/2012 15:51:09 24.2
4/14/2012 15:52:09 99.3
How do I convert this timestamp column into a 24 hour format?
In order to make use of SQLite date/time functions and allow date comparisons (and sorting), date should be stored in YYYY-MM-DD HH:MM-SS
.
So, my answer will address your question and this date conversion:
UPDATE rawdata SET timestamp=(SELECT DATETIME(SUBSTR(timestamp, s2+1, 4)||'-01-01',
SUBSTR(timestamp, 1, s1 -1)||' months', '-1 months',
SUBSTR(timestamp, s1+1, s2-s1-1)||' days', '-1 days',
SUBSTR(timestamp, s3+1, s4-s3-1)||' hours',
SUBSTR(timestamp, s4+1, s5-s4-1)||' minutes',
SUBSTR(timestamp, s5+1, s6-s5-1)||' seconds',
CASE WHEN SUBSTR(timestamp, s3+1, s4-s3-1) = '12' THEN '-12 hours' ELSE '0 hours' END,
CASE WHEN SUBSTR(timestamp, s6+1) LIKE 'PM' THEN '+12 hours' ELSE '0 hours' END
)
FROM (
SELECT *,
INSTR(SUBSTR(timestamp, s1+1), '/')+s1 AS s2,
INSTR(SUBSTR(timestamp, s4+1), ':')+s4 AS s5,
INSTR(SUBSTR(timestamp, s3+1), ' ')+s3 AS s6
FROM (
SELECT timestamp,
INSTR(timestamp, '/') AS s1,
INSTR(timestamp, ' ') AS s3,
INSTR(timestamp, ':') AS s4
)
));
This horrible block get all separators position, reconstruct date from components and handle PM
. Note that 1...11AM => +0
and 1...11PM => +12
, but 12AM => -12
and 12PM => +0
!
Check it in SQL Fiddle.
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