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Number of rows returned by different JOINs

  • July 2, 2014 at 8:07 pm

    #288342

    Comments posted to this topic are about the item Number of rows returned by different JOINs

  • July 3, 2014 at 12:07 am

    #1726686

    Interesting one 🙂

  • July 3, 2014 at 12:57 am

    #1726690

    Way too easy as you only have to check the first query to get to the right answer.

    Thanks for the effort though.

    Need an answer? No, you need a question
    My blog at https://sqlkover.com.
    MCSE Business Intelligence - Microsoft Data Platform MVP

  • July 3, 2014 at 2:16 am

    #1726700

    Finally a question for my level.

    Thanks

  • July 3, 2014 at 2:24 am

    #1726705

    Koen Verbeeck (7/3/2014)

    Way too easy as you only have to check the first query to get to the right answer.

    Thanks for the effort though.

    +1

    (did the same) Thank you for the post, nice one.

    ww; Raghu
    --
    The first and the hardest SQL statement I have wrote- "select * from customers" - and I was happy and felt smart.

  • July 3, 2014 at 2:58 am

    #1726711

    Definitely way too easy.

    Still easy, but if table B would have the values 1 and 2, then at least you could have explained something about the different join types.

  • July 3, 2014 at 3:04 am

    #1726712

    Mighty (7/3/2014)

    Definitely way too easy.

    Still easy, but if table B would have the values 1 and 2, then at least you could have explained something about the different join types.

    This should hold for some time... (except CROSS)

    ww; Raghu
    --
    The first and the hardest SQL statement I have wrote- "select * from customers" - and I was happy and felt smart.

  • July 3, 2014 at 4:11 am

    #1726724

    Raghavendra Mudugal (7/3/2014)

    Koen Verbeeck (7/3/2014)

    Way too easy as you only have to check the first query to get to the right answer.

    Thanks for the effort though.

    +1

    (did the same) Thank you for the post, nice one.

    +1

    Valid, only when all values are same like in the example.

    Igor Micev,My blog: www.igormicev.com

  • July 3, 2014 at 4:45 am

    This was removed by the editor as SPAM

  • July 3, 2014 at 5:16 am

    #1726742

    Nice question, thanks for sharing

  • July 3, 2014 at 6:26 am

    #1726766

    Stewart "Arturius" Campbell (7/3/2014)

    Found myself thinking this was way too easy, where's the catch?

    only to find there wasn't one

    Nice question, thanks Abbas

    +1

    This took me way too long to answer, because I kept looking over it trying to figure out what the trick was. Ultimately I couldn't find it and went with the simple answer.

  • July 3, 2014 at 7:11 am

    #1726798

    thanks for puting it together

  • July 3, 2014 at 7:14 am

    #1726802

    Easy one, thanks. I needed an easy one after getting the last four in a row wrong.


    [font="Tahoma"]Personal blog relating fishing to database administration:[/font]
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  • July 3, 2014 at 8:22 am

    #1726843

    david.gugg (7/3/2014)

    Easy one, thanks. I needed an easy one after getting the last four in a row wrong.

    ...been there... 🙂 totally agree.

    ww; Raghu
    --
    The first and the hardest SQL statement I have wrote- "select * from customers" - and I was happy and felt smart.

  • July 3, 2014 at 9:14 am

    #1726872

    Nice question, although somewhat simple. However, the explanation given:

    The values in col1 in both the tables is matched against each other resulting in 6 rows for all the SELECT statements.

    is slightly incorrect. This statement is true for all of the join types, except the cross join, in which col1 is not matched between the tables; you just get all possible combinations. If table A contained 1,2,3, and table B contained 4,5, the cross join would still produce 6 rows.

    I suggest that you submit another QotD similar to this, but with more values in each table, such as table A containing 1,1,1,2,null,null and table B containing 1,1,3,null,null. That would be more challenging, especially with multiple nulls values to consider ("when does null=null?").

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