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which one is best query?

  • June 1, 2013 at 3:42 am

    #278435

    first query

    select COUNT(id) from tbl_birthmaster1 where status_info=1

    and zone_id=1

    select COUNT(id) from tbl_birthmaster1 where isnull(pdffilepath,'')!='' and status_info=1

    and zone_id=1

    select COUNT(id) from tbl_birthmaster1 where cfcApprove=0 and status_info=1

    and zone_id=1

    select COUNT(id) from tbl_birthmaster1 where cfcApprove=1 and mcaApprove=0 and status_info=1

    and zone_id=1

    select COUNT(id) from tbl_birthmaster1 where FormType=1 and mcaApprove=1 and DRApprove=0 and status_info=1

    and zone_id=1

    select COUNT(id) from tbl_birthmaster1 where FormType=2 and mcaApprove=1 and SDOApprove=0 and status_info=1

    and zone_id=1

    select COUNT(id) from tbl_birthmaster1 where FormType=3 and mcaApprove=1 and CRApprove=0 and status_info=1

    and zone_id=1

    second one is--

    SELECT

    sum(CASE WHEN status_info = 1 and zone_id=1 then 1 else 0 end) AS count1,

    sum(CASE WHEN isnull(pdffilepath,'')!='' AND status_info=1 and zone_id=1 then 1 else 0 end) AS count2,

    sum(CASE WHEN cfcApprove=0 and status_info=1 and zone_id=1 then 1 else 0 end) AS count3,

    sum(CASE WHEN cfcApprove=1 and mcaApprove=0 and status_info=1 and zone_id=1 then 1 else 0 end) AS count4,

    sum(CASE WHEN FormType=1 and mcaApprove=1 and DRApprove=0 and status_info=1 and zone_id=1 then 1 else 0 end) AS count5,

    sum(CASE WHEN FormType=2 and mcaApprove=1 and SDOApprove=0 and status_info=1 and zone_id=1 then 1 else 0 end) AS count6,

    sum(CASE WHEN FormType=3 and mcaApprove=1 and CRApprove=0 and status_info=1 and zone_id=1 then 1 else 0 end) AS count7

    FROM tbl_birthmaster1

  • June 1, 2013 at 3:43 am

    #1620268

    second one

  • June 1, 2013 at 3:38 pm

    #1620298

    I don't there is a choice of which is "best". The "first query" is not a single query, it is several of them. It depends on what you want as output. I would think the performance wise the second option would be faster.

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  • June 2, 2013 at 1:00 pm

    #1620343

    It depends also how many data do you have and what indexes are there.

  • June 2, 2013 at 8:50 pm

    #1620363

    Considering the low selectivity of the criteria, they're both going to making sucking sounds. If you index to increase their SELECT performance, they'll likely timeout on inserts because of that same low selectivity which will cause massive extent splits.

    Considering that, the second "query" probably stands a better chance because it'll only do 1 table scan. As has been pointed out, though, they first returns data in an unpivoted format and the second returns the data in a pivoted format.

    You might be able to get a bit more performance out of both is you change {where isnull(pdffilepath,'')!=''} to {where pdfilepath > ''} which will also knock out the nulls and removes the column from the function.

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