Inner Join question

  • I have 2 queries below. Both before the exame same as far as performance and result. Is there a best or preferred method or does it depend on the one writing the query?

    select cf.VCN

    --,cf.deficientClaimForm, cf.reviewStatusID, d1.bgReceivedDate as [Event 10 Date], d8.bgReceivedDate as [Event 88 Date]

    from tblClaimForms cf

    inner join

    (select foreignKeyID, bgReceivedDate

    from tblDocuments

    where documentTypeID = 10) d1 on d1.foreignKeyID = cf.VCN

    inner join

    (select foreignKeyID, bgReceivedDate

    from tblDocuments

    where documentTypeID = 88) d8 on d8.foreignKeyID = cf.VCN

    where cf.deficientClaimForm = 1

    and cf.reviewStatusID = 1

    and ((d8.bgReceivedDate > d1.bgReceivedDate) or (d8.bgReceivedDate = d1.bgReceivedDate))

    --------------------------

    select cf.VCN

    ,cf.deficientClaimForm, cf.reviewStatusID, d1.bgReceivedDate as [Event 10 Date], d8.bgReceivedDate as [Event 88 Date]

    from tblClaimForms cf

    inner join tblDocuments d1 on d1.foreignKeyID = cf.VCN

    inner join tblDocuments d8 on d8.foreignKeyID = cf.VCN

    where d1.documentTypeID = 10

    and d8.documentTypeID = 88

    and cf.deficientClaimForm = 1

    and cf.reviewStatusID = 1

    and ((d8.bgReceivedDate > d1.bgReceivedDate) or (d8.bgReceivedDate = d1.bgReceivedDate))

  • Check the query plans and if they are the same it really doesn't matter. I prefer the second because I find it easier to read.

  • I'd tend to go with the second one, all other things being equal.

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  • Assuming the query plans are the same, I'd tend to go with the second one as well.

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    Author of:
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