假设我有一个名为'importscript.sql'的脚本来创建一个表,并从名为'rawdata.txt'的文本文件中填充它,如下所示:
CREATE TABLE rawdata (
timestamp text,
value REAL
);
.separator ,
.import '~/path of the file/rawdata.txt' rawdata
'rawdata.txt'文件如下所示:
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
然后使用以下命令创建一个名为RAWDATA.db的数据库,其中包含rawdata表:
sqlite3 RAWDATA.db < ~/path to the script/importscript.sql
导入完成后的表格如下所示:
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
但我希望它看起来像这样
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
如何将此时间戳列转换为24小时格式?
答案 0 :(得分:4)
为了使用SQLite日期/时间函数并允许日期比较(和排序),日期应存储在YYYY-MM-DD HH:MM-SS
。
所以,我的回答将解决您的问题和日期转换:
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
)
));
这个可怕的块获取所有分隔符位置,从组件重建日期并处理PM
。请注意1...11AM => +0
和1...11PM => +12
,但12AM => -12
和12PM => +0
!
在SQL Fiddle中查看。