mysql选择min(time),其中date col为min(date)

SELECT min(a.timecol), a.datecol, a.daycol FROM `timetable` a 
  WHERE a.datecol = (
      SELECT min(b.datecol) from `timetable` b
  )

这将返回2019年1月16日08:30行。

你可以试试:

select timecol as MinTime from myTable where daycol = '1' order by datecol ASC limit 1

应该这样做:

SELECT
    MIN( timecol ) AS MinTime
FROM myTable
WHERE daycol = '1'
AND datecol = (
    SELECT
        MIN( datecol )
    FROM myTable
    WHERE daycol = '1'
)
;

如果运行的是MySQL8或更高版本(或任何支持DB的窗口函数),则:

SELECT
    daycol, datemin, timemin
FROM (
    SELECT
        *
      , MIN( datecol ) OVER (PARTITION BY daycol) datemin
      , MIN( timecol ) OVER (PARTITION BY daycol, datecol) timemin
    FROM myTable
) d
WHERE daycol = '1'
AND datecol = datemin
AND timecol = timemin

这将给出日期列最小的时间列的最小值。 从myTable中选择min(timecol)作为mintime,其中datecol=(从myTable中选择min(datecol));

确保timecol和datecol分别为日期和时间类型。