SQL查找日期有最大记录

Question

I have a tbl_transaction table in MySQL database. with format like below:

tbl_transaction  (
    trans_id: int
    trans_time: timestamp
    amount: float
)

I want to write SQLs to

1. to find the Day which have count of records ( in table tbl_transaction) is max
2. to find the Hour which have count of records ( in table tbl_transaction) is max

Thanks

Answer 1

Try this for sql server..

SELECT datepart(dd,trans_time) AS DAY,
       datepart(hh,trans_time) AS Hours
FROM tbl_transaction
WHERE trans_id =
    (SELECT trans_id
     FROM tbl_transaction
     GROUP BY trans_id having count(trans_id)=max(count(trans_id)))

for Mysql

  SELECT Day(dd,trans_time) AS DAY,
           Hour(hh,trans_time) AS Hours
    FROM tbl_transaction
    WHERE trans_id =
        (SELECT max(trans_id)
         FROM tbl_transaction
          trans_id having count(trans_id)=max(count(trans_id)))

Answer 2

Count By Date:

select 
    count(`trans_id`) as TCount,
    DATE(`trans_time`) as `Date`
from `tbl_transaction`
group by DATE(`trans_time`)

Count By Hour:

select 
    count(`trans_id`) as TCount,
    HOUR(`trans_time`) as `Hour`
from `tbl_transaction`
group by HOUR(`trans_time`)

Answer 3

You would use group by , order by , and limit . For the date:

select date(trans_time), count(*)
from tbl_transaction
group by date(trans_time)
order by count(*) desc
limit 1;

For the hour (assuming you mean hour and day):

select date(trans_time), hour(trans_time), count(*)
from tbl_transaction
group by date(trans_time), hour(trans_time)
order by count(*) desc
limit 1;