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Thread: Randomly returning rows

  1. #1
    Registered Mike's Avatar
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    Randomly returning rows

    Hi all,

    I would like to randomly return rows from a basic database. I would do this through rand() but it would take quite a while with all the if statements imho.

    So can anyone think of a quicker way?

    Thanks,
    Mike
    Don't you just love free internet games ?

  2. #2
    Senior Member chromate's Avatar
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    if statements?

    Just count the number of rows returned and set the range of the rand function from 0 to count_num_rows($result). Then use the number returned to pull that row from the results.

    Is this what you mean?

  3. #3
    Registered Mike's Avatar
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    Sorry, I should have explained better. I want about ten results to be returned, that's why I said if statements.

    Or would you just do what you said ten times?
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  4. #4
    Administrator Chris's Avatar
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    If you knew the total number of rows you can generate 10 random numbers and then query the DB with those in a single query (where rowid in (55, 56, 87,...)
    Chris Beasley - My Guide to Building a Successful Website[size=1]
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  5. #5
    Registered Mike's Avatar
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    Hmm... do you know of a tutorial Chris please?

    Thanks,
    Mike
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  6. #6
    Administrator Chris's Avatar
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    An SQL tutorial covering where statements should show an example.
    Chris Beasley - My Guide to Building a Successful Website[size=1]
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  7. #7
    Senior Member chromate's Avatar
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    PHP Code:
    for ($i=0$i 10$i++) {
       
    $rnd_row rand(0$total_rows);
       if (
    $i 0$row_ids "rowid = '$rnd_row' ";
       
    $row_ids .= "OR rowid = '$rnd_row' ";
    }

    $sql "SELECT * FROM blah WHERE $row_ids";
    $result mysql_query($sql$db); 
    Something like that... Probably wont work right first time... I just bashed it out quickly cause I don't have much time

  8. #8
    Registered Mike's Avatar
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    I'll try it tomorrow, thanks Chromate
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  9. #9
    Half of it is 70% smarts Nick's Avatar
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    You could also put all the rows into an array, and use a random number to pull from the array.

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