Question

I need to group stockmarket “1min” data with {Name, DateTime, Open, High, Low, Close, Volume} into different timeframes ie. “5mins/15mins/60mins” on MYSQL. Schema built on sqlfiddle – http://sqlfiddle.com/#!2/91433.

I found a link – Group OHLC-Stockmarket Data into multiple timeframes with T-SQL with similar requirement for MSSQL.

I tried to follow the link – http://briansteffens.com/2011/07/19/row_number-partition-and-over-in-mysql/, to get row_number(), over, partition in mysql to solve the issue.

I am a newbie to sql, can anyone please point me in the right direction?

Answer 1

Finally resolved the issue with the following mysql query:

select min(a.mydate),max(a.myhigh) as high,min(a.mylow) as low, 
min(case when rn_asc = 1 then a.myopen end) as open,
min(case when rn_desc = 1 then b.myclose end) as close

from( 

select 
@i := if((@lastdate) != (Floor(unix_timestamp(mydate)/300 )), 1, @i + 1) as rn_asc,
          mydate, myhigh, mylow, myopen, myclose,
          @lastdate := (Floor(unix_timestamp(mydate)/300 ))

from
  onemindata_1,
  (select @i := 0) vt1,
  (select @lastdate := null) vt2 order by mydate

) a

inner join(

select 
@j := if((@lastdate1) != (Floor(unix_timestamp(mydate)/300 )), 1, @j + 1) as rn_desc,
          mydate,myclose,
          @lastdate1 := (Floor(unix_timestamp(mydate)/300 ))

from
  onemindata_1,
  (select @j := 0) vt1,
  (select @lastdate1 := null) vt2 order by mydate desc

)b
on a.mydate=b.mydate
group by (Floor(unix_timestamp(a.mydate)/300 ))

Toughest part was to get the Open and Close for the “Specific Time Intervals”. I am doing an inner join of ‘high,low,open’ with ‘close’ on ‘date’. I can switch the time intervals by changing the denominator in (Floor(unix_timestamp(mydate)/300 )). Currently not worried about the performance as long as it works :).