组合顺序日期

Question

我的表格中有以下数据

基于shift_id我希望合并轮班日期。

简而言之，我想要以下输出：

**output format : FromDate To ToDate (Shift_id)**

2012-12-01 To 2012-12-02 (2)

2012-12-03 (1)

2012-12-04 (2)

2012-12-18 To 2012-12-20 (1)

2012-12-21 To 2012-12-22 (2)

2012-12-23 To 2012-12-24 (1)

2012-12-25 To 2012-12-30 (2)

我尝试过几件事，但没有运气。任何人请帮助/指导我解决这个问题。

我写了这段代码

    while($row_shift = mysql_fetch_object($result_shift)) {
    $new_date = $row_shift->shift_date;
    $new_shift = $row_shift->shift_id;
    if($new_shift !== $old_shift) {
        $shift_name = $new_shift;
        $shift_date_1 =  date('D d M',strtotime($new_date))." (".$shift_name.")";               
    } else {
        $shift_name = $old_shift;
        $shift_date_1 =  date('D d M',strtotime($old_date))." (".$shift_name.")";
        $diff = abs(floor( (strtotime($new_date) - strtotime($old_date)) / 3600 / 24));
        if($diff == 1) {                    
            $to_part = ' To ';
            $shift_date_2 = date('D d M',strtotime($new_date))." (".$shift_name.")";

        } else {
            $to_part = ' To ';
            $shift_date_2 = date('D d M',strtotime($old_date))." (".$shift_name.")";    
        }
    }

    $s_d_2 = $to_part.$shift_date_2;

    $shift_date[] = $shift_date_1.$s_d_2;

    $old_date = $row_shift->shift_date;
    $old_shift = $row_shift->shift_id;

}
echo implode("<br/>", $shift_date);

并且此代码的​​输出为

Output : 
Sat 01 Dec (2)
Sat 01 Dec (2) To Sun 02 Dec (2)
Mon 03 Dec (1)Sun 02 Dec (2)
Tue 04 Dec (2)Sun 02 Dec (2)
Tue 18 Dec (1)Sun 02 Dec (2)
Tue 18 Dec (1) To Wed 19 Dec (1)
Wed 19 Dec (1) To Thu 20 Dec (1)
Fri 21 Dec (2)Thu 20 Dec (1)
Fri 21 Dec (2) To Sat 22 Dec (2)
Sun 23 Dec (1)Sat 22 Dec (2)
Sun 23 Dec (1) To Mon 24 Dec (1)
Tue 25 Dec (2)Mon 24 Dec (1)
Tue 25 Dec (2) To Wed 26 Dec (2)
Wed 26 Dec (2) To Thu 27 Dec (2)
Thu 27 Dec (2) To Fri 28 Dec (2)
Fri 28 Dec (2) To Sat 29 Dec (2)
Sat 29 Dec (2) To Sun 30 Dec (2)

感谢。

Answer 1

这是SQLFiddle demo

select min(shift_date) start_data,max(shift_date) end_date,
          min(Shift_id) Shift_id
from
(
select t.*,if(shift_id<>@CurShift,@i:=@i+1,@i) Group_num,
       @CurShift:=shift_id 
from t, (select @CurShift:=0,@i:=0) t1 
order by shift_date
 ) b

group by Group_num
order by Group_num