Question

我将日期存储为sqlite数据库中的字符串，如“28/11/2010”。我想将字符串转换为日期。

具体来说，我必须在两个日期之间转换大量的字符串日期。

在postgresql中，我使用to_date('30/11/2010','dd/MM/yyyy')，我怎么能用sqlite做同样的事情？

这样的事情：

SELECT * FROM table
    WHERE   to_date(column,'dd/MM/yyyy')
    BETWEEN to_date('01/11/2010','dd/MM/yyyy')
    AND     to_date('30/11/2010','dd/MM/yyyy')

Answer 1

作为Sqlite doesn't have a date type，您需要进行字符串比较才能实现此目的。要做到这一点，你需要扭转顺序 - 例如从dd / MM / yyyy到yyyyMMdd，使用像

这样的东西

where substr(column,7)||substr(column,4,2)||substr(column,1,2) 
      between '20101101' and '20101130'

Answer 2

保存日期为TEXT（20/10/2013 03:26）要进行查询并在日期之间选择记录吗？

更好的版本是：

SELECT TIMSTARTTIMEDATE 
FROM TIMER 
WHERE DATE(substr(TIMSTARTTIMEDATE,7,4)
||substr(TIMSTARTTIMEDATE,4,2)
||substr(TIMSTARTTIMEDATE,1,2)) 
BETWEEN DATE(20131020) AND DATE(20131021);

2013年10月20日的substr给出了20131020 日期格式DATE（20131021） - 使SQL使用日期并使用日期和时间函数。

OR

SELECT TIMSTARTTIMEDATE 
FROM TIMER 
WHERE DATE(substr(TIMSTARTTIMEDATE,7,4)
||'-'
||substr(TIMSTARTTIMEDATE,4,2)
||'-'
||substr(TIMSTARTTIMEDATE,1,2)) 
BETWEEN DATE('2013-10-20') AND DATE('2013-10-21');

，这是一行

SELECT TIMSTARTTIMEDATE FROM TIMER WHERE DATE(substr(TIMSTARTTIMEDATE,7,4)||'-'||substr(TIMSTARTTIMEDATE,4,2)||'-'||substr(TIMSTARTTIMEDATE,1,2)) BETWEEN DATE('2013-10-20') AND DATE('2013-10-21');

Answer 3

你应该研究的一件事是SQLite date and time functions，特别是如果你不得不操纵很多日期。这是使用日期的理智方式，代价是更改内部格式（必须是ISO，即yyyy-MM-dd）。

Answer 4

与脆弱的substr值相比，我更喜欢UDF方法。

#!/usr/bin/env python3
import sqlite3
from dateutil import parser
from pprint import pprint


def date_parse(s):
    ''' Converts a string to a date '''
    try:
        t = parser.parse(s, parser.parserinfo(dayfirst=True))
        return t.strftime('%Y-%m-%d')
    except:
        return None


def dict_factory(cursor, row):
    ''' Helper for dict row results '''
    d = {}
    for idx, col in enumerate(cursor.description):
        d[col[0]] = row[idx]
    return d


def main():
    ''' Demonstrate UDF '''
    with sqlite3.connect(":memory:") as conn:
        conn.row_factory = dict_factory
        setup(conn)

        ##################################################
        # This is the code that matters. The rest is setup noise.
        conn.create_function("date_parse", 1, date_parse)
        cur = conn.cursor()
        cur.execute(''' select "date", date_parse("date") as parsed from _test order by 2; ''')
        pprint(cur.fetchall())
        ##################################################

def setup(conn):
    ''' Setup some values to parse '''
    cur = conn.cursor()

    # Make a table
    sql = '''
    create table _test (
        "id" integer primary key,
        "date" text
    );
    '''
    cur.execute(sql)

    # Fill the table
    dates = [
        '2/1/03', '03/2/04', '4/03/05', '05/04/06',
        '6/5/2007', '07/6/2008', '8/07/2009', '09/08/2010',
        '2-1-03', '03-2-04', '4-03-05', '05-04-06',
        '6-5-2007', '07-6-2008', '8-07-2009', '09-08-2010',
        '31/12/20', '31-12-2020',
        'BOMB!',
    ]
    params = [(x,) for x in dates]
    cur.executemany(''' insert into _test ("date") values(?); ''', params)


if __name__ == "__main__":
    main()

这将为您提供以下结果：

[{'date': 'BOMB!', 'parsed': None},
 {'date': '2/1/03', 'parsed': '2003-01-02'},
 {'date': '2-1-03', 'parsed': '2003-01-02'},
 {'date': '03/2/04', 'parsed': '2004-02-03'},
 {'date': '03-2-04', 'parsed': '2004-02-03'},
 {'date': '4/03/05', 'parsed': '2005-03-04'},
 {'date': '4-03-05', 'parsed': '2005-03-04'},
 {'date': '05/04/06', 'parsed': '2006-04-05'},
 {'date': '05-04-06', 'parsed': '2006-04-05'},
 {'date': '6/5/2007', 'parsed': '2007-05-06'},
 {'date': '6-5-2007', 'parsed': '2007-05-06'},
 {'date': '07/6/2008', 'parsed': '2008-06-07'},
 {'date': '07-6-2008', 'parsed': '2008-06-07'},
 {'date': '8/07/2009', 'parsed': '2009-07-08'},
 {'date': '8-07-2009', 'parsed': '2009-07-08'},
 {'date': '09/08/2010', 'parsed': '2010-08-09'},
 {'date': '09-08-2010', 'parsed': '2010-08-09'},
 {'date': '31/12/20', 'parsed': '2020-12-31'},
 {'date': '31-12-2020', 'parsed': '2020-12-31'}]

SQLite相当于任何强大的东西，是你应该避免的substr和instr调用的混乱编织。

Answer 5

这是针对fecha（TEXT）格式的日期YYYY-MM-dd HH：mm：ss例如我想要Ene-05-2014（2014-01-05）的所有记录：

SELECT 
 fecha 
FROM 
 Mytable 
WHERE 
 DATE(substr(fecha ,1,4) ||substr(fecha ,6,2)||substr(fecha ,9,2))
BETWEEN 
 DATE(20140105) 
AND 
 DATE(20140105);

Answer 6

我将日期存储为DD-MON-YYYY格式（2016年6月10日），以下查询适用于我搜索2个日期之间的记录。

select date, substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2),  case 
substr(date, 4,3) 
when 'Jan' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Jan' , '01')) 
when 'Feb' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Feb' , '02')) 
when 'Mar' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Mar' , '03')) 
when 'Apr' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Apr' , '04')) 
when 'May' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'May' , '05')) 
when 'Jun' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Jun' , '06')) 
when 'Jul' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Jul' , '07')) 
when 'Aug' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Aug' , '08')) 
when 'Sep' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Sep' , '09')) 
when 'Oct' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Oct' , '10')) 
when 'Nov' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Nov' , '11')) 
when 'Dec' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Dec' , '12')) 
else '0' end as srcDate from payment where srcDate >= strftime('%s', '2016-07-06') and srcDate <= strftime('%s', '2016-09-06');

Answer 7

如果源日期格式不一致则存在一些问题使用substr函数，例如：

1/1/2017 或 1/11/2017 或 11/11 / 2017 或 1/1/17 等。

所以我使用临时表跟着不同的apporach。此代码段输出＆＃39; YYYY-MM-DD＆＃39; +时间，如果存在。

请注意，此版本接受日/月/年格式。如果你想要月/日/年交换前两个变量DayPart和MonthPart。此外，两年的日期＆＃39; 44 - ＆＃99; 99假设1944-1999，而＆＃39;＆＃39; 43假设2000-2043。

 BEGIN;

    CREATE TEMP TABLE [DateconvertionTable] (Id TEXT PRIMARY KEY, OriginalDate  TEXT  , SepA  INTEGER,  DayPart TEXT,Rest1 TEXT, SepB  INTEGER,  MonthPart TEXT, Rest2 TEXT, SepC  INTEGER,  YearPart TEXT, Rest3 TEXT, NewDate TEXT);
    INSERT INTO [DateconvertionTable] (Id,OriginalDate)  SELECT SourceIdColumn, SourceDateColumn From  [SourceTable];

    --day Part (If day is first)

    UPDATE [DateconvertionTable] SET SepA=instr(OriginalDate ,'/');
    UPDATE [DateconvertionTable] SET DayPart=substr(OriginalDate,1,SepA-1) ;
    UPDATE [DateconvertionTable] SET Rest1=substr(OriginalDate,SepA+1);

    --Month Part (If Month is second)

    UPDATE [DateconvertionTable] SET SepB=instr(Rest1,'/');
    UPDATE [DateconvertionTable]  SET MonthPart=substr(Rest1, 1,SepB-1);
    UPDATE [DateconvertionTable] SET Rest2=substr(Rest1,SepB+1);

    --Year Part (3d)

    UPDATE [DateconvertionTable] SET SepC=instr(Rest2,' ');

           --Use Cases In case of time string included
    UPDATE [DateconvertionTable]  SET YearPart= CASE WHEN SepC=0 THEN Rest2 ELSE substr(Rest2,1,SepC-1)  END;

           --The Rest considered time
    UPDATE [DateconvertionTable]  SET Rest3= CASE WHEN SepC=0 THEN  '' ELSE substr(Rest2,SepC+1) END;

           -- Convert 1 digit day and month to 2 digit
    UPDATE [DateconvertionTable] SET DayPart=0||DayPart WHERE CAST(DayPart AS INTEGER)<10;
    UPDATE [DateconvertionTable] SET MonthPart=0||MonthPart WHERE CAST(MonthPart AS INTEGER)<10;

           --If there is a need to convert 2 digit year to 4 digit year, make some assumptions...
    UPDATE [DateconvertionTable] SET YearPart=19||YearPart WHERE CAST(YearPart AS INTEGER)>=44 AND CAST(YearPart AS INTEGER)<100;
    UPDATE [DateconvertionTable] SET YearPart=20||YearPart WHERE CAST(YearPart AS INTEGER)<44 AND CAST(YearPart AS INTEGER)<100;

    UPDATE [DateconvertionTable] SET NewDate = YearPart  || '-' || MonthPart || '-' || DayPart || ' ' || Rest3;  

    UPDATE [SourceTable] SET SourceDateColumn=(Select NewDate FROM DateconvertionTable WHERE [DateconvertionTable].id=SourceIdColumn);
    END;

Answer 8

我有一个数据库，其中日期以d F Y格式存储（2017年11月20日），并将其转换为机器可读的日期（Ymd），我使用此方法将整个表格更新为正确的格式。 / p>

如果只希望日期格式化，请查看内部，选择我格式化日期的方式。

update TABLENAME as realTABLE set created_at = (
select 
    -- Get Year
    substr(tmpTABLE.created_at ,-4, 4)
     || '-' ||
     -- Get Month
      substr(
           replace (replace (replace (replace (replace (replace (replace (replace (replace (replace (replace (replace (tmpReis.szAanmaakDatum
           , ' Dec ', '-12-') , ' Nov ', '-11-') , ' Oct ', '-10-') , ' Sep ', '-09-') , ' Aug ', '-08-') , ' Jul ', '-07-') , ' Jun ', '-06-') , ' May ', '-05-') , ' Apr ', '-04-') , ' Mar ', '-03-') , ' Feb ', '-02-') , ' Jan ', '-01-')
           -- Get it from the original space location + 1, then get the two numbers.
           ,instr(tmpTABLE.created_at, ' ')+1, 2)
     || '-' ||
     -- Get day, prepend with a zero if there's a zero lacking.
     substr('00' || tmpTABLE.created_at, -2, 2) as foo
from TABLENAME as tmpTABLE 
where tmpTABLE.id = realTABLE.id    
-- Check for valid matching formats. don't do those that already were converted.
) where created_at like '_ ___ ____' 
or created_at like '__ ___ ____';

Answer 9

将 string 转换为 date 小问题认为索引 mmm 3,3 但工作添加了一个月到日期字符串

SELECT substr('12Jan20',1,2) as dday,
date(substr('12Jan20',6,7) ||'00-' || case substr('12Jan20',3,3) when 'Jan' then '01'
when 'Feb' then '02'
when 'Mar' then '03'
when 'Apr' then '04'
when 'May' then '05' 
when 'Jun' then '06'
when 'Jul' then '07'
when 'Aug' then '08'
when 'Sep' then '09'
when 'Oct' then '10'
when 'Nov' then '11'
when 'Dec' then '12' end  || '-'||substr('12Jan20',1,2), '+1 month') as tt

Sqlite将字符串转换为日期

9 个答案: