Always LEFT JOIN Grandchild?

• Steve Dingle

  SSChasing Mays

  Points: 601

  More actions

  December 16, 2006 at 6:37 am

  #92054

  Hello All,

  This might seem like a silly question but I was wondering what the "best practice" was when I have a PARENT - CHILD - GRANDCHILD scenario and I'm LEFT JOINing the CHILD should I also LEFT JOIN the GRANDHCILD even if I don't need to. For instance say I have Customer, Invoice, LineItem. Customer may not have invoices but every invoice has line item. Say I want to get list of all customer in 'GA', along with invoice totals. Should my JOIN be like

  SELECT

  FROM CUSTOMER

  LEFT JOIN INVOICE

  LEFT JOIN LINEITEM

  or can I do

  SELECT

  FROM CUSTOMER

  LEFT JOIN INVOICE

  JOIN LINEITEM

  Since I know that all invoice will have a line item. FWIW, I currently do a LEFT JOIN, just starting to quetion if I have too. In testing I have been getting the same results

  Thanks

  Steve

  ---

  Much Thanks,

  Steve Dingle

• Jo Pattyn

  SSC-Dedicated

  Points: 32348

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  December 16, 2006 at 8:23 am

  #678516

  nr 2.

  You can use the inner join. The results for invoice,lineitem will be null if no matching customer is found.