日期范围内每天的棘手mysql计数

Question

I'm having trouble with getting the records for the following

TABLE
id | holiday_From | holiday_To
1  | 2012-01-02   | 2012-01-03
1  | 2012-01-11   | 2012-01-16
1  | 2012-01-08   | 2012-01-22
1  | 2012-01-29   | 2012-01-30
1  | 2012-01-08   | 2012-01-11

I'm trying to get occurrences of holidays for a given month - ie

BETWEEN "2012-01-01" AND "2012-01-31"

there is a similar post but im unable to tweak it for my needs

RESULT
day (within range) | count() //number of ppl on holiday
DATE               | 3

for eg

SAMPLE OUTPUT
2012-01-02 | 1
2012-01-03 | 1
2012-01-08 | 2
2012-01-09 | 2
2012-01-10 | 2
2012-01-11 | 3
2012-01-12 | 2
2012-01-13 | 2
2012-01-14 | 2
2012-01-15 | 2
2012-01-16 | 2
......

In other words I am trying to get how many times a record is found for a specific date. Ie how many people are on holiday on the 1st, 2nd 3nd etc.

Not every day is in the TABLE for each month

Any ideas?

ps this is what i have already (my shot in the dark)

SELECT h.holiday_From, h.holiday_To, COUNT( * )
FROM holiday h
JOIN holiday ho ON h.holiday_From
BETWEEN DATE( "2012-01-01" )
AND IF( DATE( "2012-01-31" ) , DATE( "2012-01-31" ) , DATE( "2012-01-01" ) )
GROUP BY h.holiday_From, h.holiday_To

Answer 1

Please, do not be scared :))

Based on generate days from date range

select d.everyday, count(*) from (select @rownum:=@rownum+1, date('2012-01-01') + interval (@rownum-1) day everyday from
(select 0 union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) t,
(select 0 union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) t2,
(select 0 union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) t3,
(SELECT @rownum:=0) r WHERE @rownum < DAY(LAST_DAY('2012-01-01'))) d, tablename tbl WHERE d.everyday>=tbl.hFrom AND d.everyday<tbl.hTo GROUP BY d.everyday

Result:

2012-01-02  1
2012-01-08  2
2012-01-09  2
2012-01-10  2
2012-01-11  2
2012-01-12  2
2012-01-13  2
2012-01-14  2
2012-01-15  2
2012-01-16  1
2012-01-17  1
2012-01-18  1
2012-01-19  1
2012-01-20  1
2012-01-21  1
2012-01-29  1

ps: I renamed columns to hFrom and hTo

pps: updated variant for the range of dates

select d.everyday, count(*) from (select @rownum:=@rownum+1, date('2012-01-01') + interval (@rownum - 1) day everyday from
(select 0 union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) t,
(select 0 union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) t2,
(select 0 union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) t3,
(SELECT @rownum:=0) r WHERE @rownum <= DATEDIFF('2012-01-11','2012-01-01')) d, `test` tbl WHERE d.everyday BETWEEN tbl.hFrom AND tbl.hTo GROUP BY d.everyday

Updated - number 2 was missing from all the unions. it should not significantly affect anything.

Answer 2

Have you tried something like this?

http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_last-day

This function will give you the last day of a month regardless of the variables involved like month/leapyear/etc...

That might be the problem you were having. It's not exactly clear...

SELECT h.holiday_From, h.holiday_To, COUNT( * )
FROM holiday h
JOIN holiday ho 
    ON h.holiday_From BETWEEN DATE( "2012-01-01" ) AND LAST_DAY("2012-01-01" )
GROUP BY h.holiday_From, h.holiday_To