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Question

我想根据日期和时间对表格进行排序。我的数据库在日期和时间上有两个单独的列，它们分别存储为字符串dd-MM-yyyy和HH：mm am / pm。如何对它们进行排序，以便最新条目显示在顶部？

Answer 1

您存储在数据库中的日期格式不具有可比性，因此您将始终必须处理此类问题。
最好将日期格式更改为YYYY-MM-DD，将时间格式更改为hh:mm。
在此期间，您可以使用substr()：

select * from tablename
order by 
  substr(datecol, 7) || substr(datecol, 4, 2)  || substr(datecol, 1, 2) DESC, 
  case length(timecol)
    when 8 then substr(timecol, 7) || substr(timecol, 1, 5)
    when 7 then substr('0' || timecol, 7) || substr('0' || timecol, 1, 5)
  end DESC

将datecol和timecol更改为您的列名称。
这样会将日期格式更改为HHHHMMDD，将时间格式更改为AM/PM mm:HH，这些格式将仅在ORDER BY中使用。
正如我之前提到的，正确的解决方案是永久更改日期和时间的格式。

Answer 2

我相信以下内容可以满足您的要求（假设表的名称为 mytable ，日期列的名称为 the_date ，时间列的名称为 the_time （显然会相应地更改这些值）：-

SELECT *
FROM mytable 
ORDER BY
    CASE 
        WHEN (substr(the_date,2,1) = '-') AND (substr(the_date,4,1) = '-') THEN substr(the_date,5,4)||'0'||substr(the_date,3,1)||'0'||substr(the_date,1,1)
        WHEN substr(the_date,2,1) = '-' AND substr(the_date,5,1) = '-' THEN substr(the_date,6,4)||substr(the_date,3,2)||'0'||substr(the_date,1,1)
        WHEN substr(the_date,3,1) = '-' AND substr(the_date,5,1) = '-' THEN substr(the_date,6,4)||'0'||substr(the_date,4,1)||substr(the_date,1,2)
      WHEN substr(the_date,3,1) = '-' AND substr(the_date,6,1) = '-' THEN substr(the_date,7,4)||substr(the_date,4,2)||substr(the_date,1,2)
    END DESC
    ,
    CASE
        WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 4 AND instr(the_time,' am') THEN '0'||substr(the_time,1,1)||'0'||substr(the_time,3,1)
        WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' am') THEN '0'||substr(the_time,1,1)||substr(the_time,3,2)  
        WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 4 AND instr(the_time,' pm') THEN CAST(12 + CAST(substr(the_time,1,1) AS INTEGER) AS TEXT)||'0'||substr(the_time,3,1)
        WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' pm') THEN CAST(12 + CAST(substr(the_time,1,1) AS INTEGER) AS TEXT)||substr(the_time,3,2)       
        WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' am') THEN substr(the_time,1,2)||'0'||substr(the_time,4,1)
        WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 6 AND instr(the_time,' am') THEN substr(the_time,1,2)||substr(the_time,4,2)       
        WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' pm') THEN CAST(12 + CAST(substr(the_time,1,2) AS INTEGER) AS TEXT)||'0'||substr(the_time,4,1)
        WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 6 AND instr(the_time,' pm') THEN CAST(12 + CAST(substr(the_time,1,2) AS INTEGER) AS TEXT)||substr(the_time,4,2)
    END DESC
;

这将处理月份中的月份，年份中的月份，小时和分钟的一位或两位数的所有排列。

它不在乎 12:00 pm 解析为24:00（也就是说，当对 pm 进行编码时，每小时会增加12点（因此即使32:00 pm将被转换（这样），并视为第44小时））。下午00:00与上午12:00相同（因为小时数增加了12点）。

上面的测试是使用：-

DROP TABLE IF EXISTS mytable;
CREATE TABLE IF NOT EXISTS mytable (the_description TEXT, the_date TEXT, the_time TEXT);
INSERT INTO mytable VALUES
    ('REC001','1-1-2019','1:15 am'),
    ('REC002','11-2-2019','11:15 am'),
    ('REC003','2-11-2019','1:15 pm'),
    ('REC004','12-10-2019','11:15 pm'),
    ('REC005','3-2-2019','12:00 am'),
    ('REC006','4-3-2018','12:00 pm'),
    ('REC007','4-3-2018','12:1 am'),
    ('REC008','4-3-2018','1:1 pm')

;
SELECT * FROM mytable;
SELECT *,
    CASE 
        WHEN substr(the_date,2,1) = '-' AND (substr(the_date,4,1) = '-') THEN substr(the_date,5,4)||'0'||substr(the_date,3,1)||'0'||substr(the_date,1,1)
        WHEN substr(the_date,2,1) = '-' AND substr(the_date,5,1) = '-' THEN substr(the_date,6,4)||substr(the_date,3,2)||'0'||substr(the_date,1,1)
        WHEN substr(the_date,3,1) = '-' AND substr(the_date,5,1) = '-' THEN substr(the_date,6,4)||'0'||substr(the_date,4,1)||substr(the_date,1,2)
      WHEN substr(the_date,3,1) = '-' AND substr(the_date,6,1) = '-' THEN substr(the_date,7,4)||substr(the_date,4,2)||substr(the_date,1,2)
    END AS SORTdate,
    CASE
        WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 4 AND instr(the_time,' am') THEN '0'||substr(the_time,1,1)||'0'||substr(the_time,3,1)
        WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' am') THEN '0'||substr(the_time,1,1)||substr(the_time,3,2)  
        WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 4 AND instr(the_time,' pm') THEN CAST(12 + CAST(substr(the_time,1,1) AS INTEGER) AS TEXT)||'0'||substr(the_time,3,1)
        WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' pm') THEN CAST(12 + CAST(substr(the_time,1,1) AS INTEGER) AS TEXT)||substr(the_time,3,2)       
        WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' am') THEN substr(the_time,1,2)||'0'||substr(the_time,4,1)
        WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 6 AND instr(the_time,' am') THEN substr(the_time,1,2)||substr(the_time,4,2)       
        WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' pm') THEN CAST(12 + CAST(substr(the_time,1,2) AS INTEGER) AS TEXT)||'0'||substr(the_time,4,1)
        WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 6 AND instr(the_time,' pm') THEN CAST(12 + CAST(substr(the_time,1,2) AS INTEGER) AS TEXT)||substr(the_time,4,2)
    END AS sorttime
FROM mytable 
ORDER BY
    CASE 
        WHEN (substr(the_date,2,1) = '-') AND (substr(the_date,4,1) = '-') THEN substr(the_date,5,4)||'0'||substr(the_date,3,1)||'0'||substr(the_date,1,1)
        WHEN substr(the_date,2,1) = '-' AND substr(the_date,5,1) = '-' THEN substr(the_date,6,4)||substr(the_date,3,2)||'0'||substr(the_date,1,1)
        WHEN substr(the_date,3,1) = '-' AND substr(the_date,5,1) = '-' THEN substr(the_date,6,4)||'0'||substr(the_date,4,1)||substr(the_date,1,2)
      WHEN substr(the_date,3,1) = '-' AND substr(the_date,6,1) = '-' THEN substr(the_date,7,4)||substr(the_date,4,2)||substr(the_date,1,2)
    END DESC
    ,
    CASE
        WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 4 AND instr(the_time,' am') THEN '0'||substr(the_time,1,1)||'0'||substr(the_time,3,1)
        WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' am') THEN '0'||substr(the_time,1,1)||substr(the_time,3,2)  
        WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 4 AND instr(the_time,' pm') THEN CAST(12 + CAST(substr(the_time,1,1) AS INTEGER) AS TEXT)||'0'||substr(the_time,3,1)
        WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' pm') THEN CAST(12 + CAST(substr(the_time,1,1) AS INTEGER) AS TEXT)||substr(the_time,3,2)       
        WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' am') THEN substr(the_time,1,2)||'0'||substr(the_time,4,1)
        WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 6 AND instr(the_time,' am') THEN substr(the_time,1,2)||substr(the_time,4,2)       
        WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' pm') THEN CAST(12 + CAST(substr(the_time,1,2) AS INTEGER) AS TEXT)||'0'||substr(the_time,4,1)
        WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 6 AND instr(the_time,' pm') THEN CAST(12 + CAST(substr(the_time,1,2) AS INTEGER) AS TEXT)||substr(the_time,4,2)
    END DESC
;

初始排序时未排序的行：-

显示具有排序顺序字段（转换的日期和时间）的已排序行：-

其他

如果日期是使用YYYY-MM-DD HH：MM（或任何公认的格式Date And Time Functions - Time Strings）存储的，则只需对列进行排序（仅需要1列）。提取多种格式的数据也非常简单。

以下是批量更新的示例，该更新会将d（d）-m（m）-yyyy和h（h）：m（m）格式（括在方括号中）将两列转换为单列值可能存在或不存在，具体取决于该值是否具有数十个数字。在示例中， the_date 和 the_time 这两个列都进行了转换：-

WITH cte1(cte1id,date,time) AS
    (
        SELECT rowid,
            CASE 
                WHEN substr(the_date,2,1) = '-' AND (substr(the_date,4,1) = '-') 
                    THEN substr(the_date,5,4)||'-0'||substr(the_date,3,1)||'-0'||substr(the_date,1,1)
                WHEN substr(the_date,2,1) = '-' AND substr(the_date,5,1) = '-' 
                    THEN substr(the_date,6,4)||'-'||substr(the_date,3,2)||'-0'||substr(the_date,1,1)
                WHEN substr(the_date,3,1) = '-' AND substr(the_date,5,1) = '-' 
                    THEN substr(the_date,6,4)||'-0'||substr(the_date,4,1)||'-'||substr(the_date,1,2)
                WHEN substr(the_date,3,1) = '-' AND substr(the_date,6,1) = '-' 
                    THEN substr(the_date,7,4)||'-'||substr(the_date,4,2)||'-'||substr(the_date,1,2)
            END AS date,
            CASE
                WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 4 AND instr(the_time,' am') 
                    THEN '0'||substr(the_time,1,1)||':0'||substr(the_time,3,1)
                WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' am') 
                    THEN '0'||substr(the_time,1,1)||':'||substr(the_time,3,2)   
                WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 4 AND instr(the_time,' pm') 
                    THEN CAST(12 + CAST(substr(the_time,1,1) AS INTEGER) AS TEXT)||':0'||substr(the_time,3,1)
                WHEN substr(the_time,2,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' pm') 
                    THEN CAST(12 + CAST(substr(the_time,1,1) AS INTEGER) AS TEXT)||':'||substr(the_time,3,2)        
                WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' am') 
                    THEN substr(the_time,1,2)||':0'||substr(the_time,4,1)
                WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 6 AND instr(the_time,' am') 
                    THEN substr(the_time,1,2)||':'||substr(the_time,4,2)        
                WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 5 AND instr(the_time,' pm') 
                    THEN CAST(12 + CAST(substr(the_time,1,2) AS INTEGER) AS TEXT)||':0'||substr(the_time,4,1)
                WHEN substr(the_time,3,1) = ':' AND instr(the_time,' ') = 6 AND instr(the_time,' pm') 
                    THEN CAST(12 + CAST(substr(the_time,1,2) AS INTEGER) AS TEXT)||':'||substr(the_time,4,2)
            END AS time
        FROM mytable 
        )
UPDATE mytable 
    SET 
        the_date = (SELECT date||' '||time FROM cte1 WHERE cte1id = mytable.rowid),
        the_time = (SELECT date||' '||time FROM cte1 WHERE cte1id = mytable.rowid)
;

下面显示了查询变得简单了多少，另外如何从转换后的表中检索接近原始格式的日期和时间（时间不是pm）：-

SELECT 
    strftime('%d-%m-%Y %H:%M',the_date) AS old_format, -- Close to original format
    * FROM mytable ORDER BY the_date DESC; -- much simpler to sort

结果是：-

列 old_format 是接近原始格式（但24小时）的日期
可以看出， the_date 和 the_time 列已转换为YYYY-MM-DD HH：MM格式，因此，最先排序的排序方式很简单可以按列（任一）按降序排序。
使用这种格式选择日期范围也非常简单。 WHERE the_date BETWEEN '2019-01-01' AND '2019-03-31'仅选择2019年前3个月的3行（从上述行中）。

如何根据日期和时间对sqlite表进行排序？

2 个答案:

初始排序时未排序的行：-

显示具有排序顺序字段（转换的日期和时间）的已排序行：-

其他