Pulling random images from a database?

[LRW]

For an e-commerce site, I'm wanting to have it pull 4 random images
for the front page from a select list of items from the DB.
I can get it to pull randomly and place the images, but I can't figure
out how to keep it from potentially repeating images; using the same
one more than once.

The best I can come up with is the following...whi ch makes duplicates
a little less common, but certainly doesn't stop it.

I'm wondering what piece of the puzzle I'm missing. Like is there an
undocumented feature of rand() that lets you exclude a number? =)

Thanks for any pointers!
Liam

$sql_home_featu re = "SELECT pr_id,pr_name,p r_thumb FROM tbl_product
WHERE pr_feature = '1'";
$result_home_fe ature = @mysql_query($s ql_home_feature , $dbh);
$num_feat_items = mysql_num_rows( $result_home_fe ature);
$x = 0;
while ($row_hfeat = mysql_fetch_arr ay($result_home _feature)) {
//$pr_id = $row_hfeat[pr_id];
$pr_name[$x] = $row_hfeat[pr_name];
$pr_thumb[$x] = $row_hfeat[pr_thumb];
$x++;
}
$a = rand(0, 4);
$homeimg1 = "<a href=\"#\"><img
src=\"prodimage s/".$pr_thumb[$a]."\"></a>";
$homeitem1 = "<img src=\"images/dotarrow.gif\"
align=\"absmidd le\">&nbsp;".$p r_name[$a];
function funb($a) {
$b = rand(0, 4);
if ($b == $a) {
$b = rand(0, 4);
return $b;
} else {
return $b;
}
}
$b = funb($a);
$homeimg2 = "<a href=\"#\"><img
src=\"prodimage s/".$pr_thumb[$b]."\"></a>";
$homeitem2 = "<img src=\"images/dotarrow.gif\"
align=\"absmidd le\">&nbsp;".$p r_name[$b];

function func($a,$b) {
$c = rand(0, 4);
if (($c == $a) || ($c == $b)) {
$c = rand(0, 4);
return $c;
} else {
return $c;
}
}
$c = func($a,$b);
$homeimg3 = "<a href=\"#\"><img
src=\"prodimage s/".$pr_thumb[$c]."\"></a>";
$homeitem3 = "<img src=\"images/dotarrow.gif\"
align=\"absmidd le\">&nbsp;".$p r_name[$c];

function fund($a,$b,$c) {
$d = rand(0, 4);
if (($d == $a) || ($d == $b) || ($d == $c)) {
$d = rand(0, 4);
return $d;
} else {
return $d;
}
}
$d = fund($a,$b,$c);
$homeimg4 = "<a href=\"#\"><img
src=\"prodimage s/".$pr_thumb[$d]."\"></a>";
$homeitem4 = "<img src=\"images/dotarrow.gif\"
align=\"absmidd le\">&nbsp;".$p r_name[$d];

[Dan Scott]

Re: Pulling random images from a database?

LRW wrote:
[color=blue]
> For an e-commerce site, I'm wanting to have it pull 4 random images
> for the front page from a select list of items from the DB.
> I can get it to pull randomly and place the images, but I can't figure
> out how to keep it from potentially repeating images; using the same
> one more than once.
>
> The best I can come up with is the following...whi ch makes duplicates
> a little less common, but certainly doesn't stop it.
>
> I'm wondering what piece of the puzzle I'm missing. Like is there an
> undocumented feature of rand() that lets you exclude a number? =)
>
> Thanks for any pointers!
> Liam
>
> $sql_home_featu re = "SELECT pr_id,pr_name,p r_thumb FROM tbl_product
> WHERE pr_feature = '1'";
> $result_home_fe ature = @mysql_query($s ql_home_feature , $dbh);
> $num_feat_items = mysql_num_rows( $result_home_fe ature);
> $x = 0;
> while ($row_hfeat = mysql_fetch_arr ay($result_home _feature)) {
> //$pr_id = $row_hfeat[pr_id];
> $pr_name[$x] = $row_hfeat[pr_name];
> $pr_thumb[$x] = $row_hfeat[pr_thumb];
> $x++;
> }
> $a = rand(0, 4);
> $homeimg1 = "<a href=\"#\"><img
> src=\"prodimage s/".$pr_thumb[$a]."\"></a>";
> $homeitem1 = "<img src=\"images/dotarrow.gif\"
> align=\"absmidd le\">&nbsp;".$p r_name[$a];
> function funb($a) {
> $b = rand(0, 4);
> if ($b == $a) {
> $b = rand(0, 4);
> return $b;
> } else {
> return $b;
> }
> }
> $b = funb($a);
> $homeimg2 = "<a href=\"#\"><img
> src=\"prodimage s/".$pr_thumb[$b]."\"></a>";
> $homeitem2 = "<img src=\"images/dotarrow.gif\"
> align=\"absmidd le\">&nbsp;".$p r_name[$b];
>
> function func($a,$b) {
> $c = rand(0, 4);
> if (($c == $a) || ($c == $b)) {
> $c = rand(0, 4);
> return $c;
> } else {
> return $c;
> }
> }
> $c = func($a,$b);
> $homeimg3 = "<a href=\"#\"><img
> src=\"prodimage s/".$pr_thumb[$c]."\"></a>";
> $homeitem3 = "<img src=\"images/dotarrow.gif\"
> align=\"absmidd le\">&nbsp;".$p r_name[$c];
>
> function fund($a,$b,$c) {
> $d = rand(0, 4);
> if (($d == $a) || ($d == $b) || ($d == $c)) {
> $d = rand(0, 4);
> return $d;
> } else {
> return $d;
> }
> }
> $d = fund($a,$b,$c);
> $homeimg4 = "<a href=\"#\"><img
> src=\"prodimage s/".$pr_thumb[$d]."\"></a>";
> $homeitem4 = "<img src=\"images/dotarrow.gif\"
> align=\"absmidd le\">&nbsp;".$p r_name[$d];[/color]

I think you're missing shuffle() (and a nice clean separation of your
presentation and logic code, but that's a different matter).

How about throwing out most of your code and using something like:
[color=blue]
> $sql_home_featu re = "SELECT pr_id,pr_name,p r_thumb FROM tbl_product
> WHERE pr_feature = '1'";
> $result_home_fe ature = @mysql_query($s ql_home_feature , $dbh);
> $num_feat_items = mysql_num_rows( $result_home_fe ature);
> $x = 0;
> while ($row_hfeat = mysql_fetch_arr ay($result_home _feature)) {
> //$pr_id = $row_hfeat[pr_id];
> $pr_name[$x] = $row_hfeat[pr_name];
> $pr_thumb[$x] = $row_hfeat[pr_thumb];
> $x++;
> }[/color]

// build an array of four numbers -- because you only want four
// images on your home page
$random_keys = array(0, 1, 2, 3);
// shuffle() is a built-in function that randomizes an array's order
shuffle($random _keys);

foreach ($random_keys as $key) {
$homeimg = '<a href="#"><img src="prodimages/' . $pr_thumb[$key] .
'"></a>';
$homeitem = '<img src="images/dotarrow.gif" align="absmiddl e">&nbsp;'
.. $pr_name[$key] . '">;
}

Dan

[steve]

Re: Pulling random images from a database?

"LRW" wrote:[color=blue]
> For an e-commerce site, I’m wanting to have it pull 4 random
> images
> for the front page from a select list of items from the DB.
> I can get it to pull randomly and place the images, but I can’t
> figure
> out how to keep it from potentially repeating images; using the[/color]
same[color=blue]
> one more than once.
>
> The best I can come up with is the following...whi ch makes[/color]
duplicates[color=blue]
> a little less common, but certainly doesn’t stop it.
>
> I’m wondering what piece of the puzzle I’m missing. Like
> is there an
> undocumented feature of rand() that lets you exclude a number? =)
>
> Thanks for any pointers!
> Liam
>
> $sql_home_featu re = "SELECT pr_id,pr_name,p r_thumb FROM[/color]
tbl_product[color=blue]
> WHERE pr_feature = ’1’";
> $result_home_fe ature = @mysql_query($s ql_home_feature , $dbh);
> $num_feat_items = mysql_num_rows( $result_home_fe ature);
> $x = 0;
> while ($row_hfeat = mysql_fetch_arr ay($result_home _feature)) {
> //$pr_id = $row_hfeat[pr_id];
> $pr_name[$x] = $row_hfeat[pr_name];
> $pr_thumb[$x] = $row_hfeat[pr_thumb];
> $x++;
> }
> $a = rand(0, 4);
> $homeimg1 = "<a href=\"#\"><img
> src=\"prodimage s/".$pr_thumb[$a]."\"></a>";
> $homeitem1 = "<img src=\"images/dotarrow.gif\"
> align=\"absmidd le\"> ".$pr_name[$a];
> function funb($a) {
> $b = rand(0, 4);
> if ($b == $a) {
> $b = rand(0, 4);
> return $b;
> } else {
> return $b;
> }
> }
> $b = funb($a);
> $homeimg2 = "<a href=\"#\"><img
> src=\"prodimage s/".$pr_thumb[$b]."\"></a>";
> $homeitem2 = "<img src=\"images/dotarrow.gif\"
> align=\"absmidd le\"> ".$pr_name[$b];
>
> function func($a,$b) {
> $c = rand(0, 4);
> if (($c == $a) || ($c == $b)) {
> $c = rand(0, 4);
> return $c;
> } else {
> return $c;
> }
> }
> $c = func($a,$b);
> $homeimg3 = "<a href=\"#\"><img
> src=\"prodimage s/".$pr_thumb[$c]."\"></a>";
> $homeitem3 = "<img src=\"images/dotarrow.gif\"
> align=\"absmidd le\"> ".$pr_name[$c];
>
> function fund($a,$b,$c) {
> $d = rand(0, 4);
> if (($d == $a) || ($d == $b) || ($d == $c)) {
> $d = rand(0, 4);
> return $d;
> } else {
> return $d;
> }
> }
> $d = fund($a,$b,$c);
> $homeimg4 = "<a href=\"#\"><img
> src=\"prodimage s/".$pr_thumb[$d]."\"></a>";
> $homeitem4 = "<img src=\"images/dotarrow.gif\"
> align=\"absmidd le\"> ".$pr_name[$d];[/color]

Use "order by rand()" in your select query, and then just limit it
to 4 rows returned.

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[LRW]

Re: Pulling random images from a database?

steve <UseLinkToEmail @dbForumz.com> wrote in message news:<41336379$ 1_3@alt.athenan ews.com>...[color=blue]
>
> Use "order by rand()" in your select query, and then just limit it
> to 4 rows returned.[/color]

Holy simple answers, Batman! That's fantastic! Totally solves my
problem, quick and easy.
I had NO idea you could use rand() in a SQL query like that.
Thanks!! =)
Liam

[LRW]

Re: Pulling random images from a database?

Dan Scott <dan.scott@ca.i bm.com> wrote in message news:<DHHYc.665 2$CG3.479445@ne ws20.bellglobal .com>...[color=blue]
> LRW wrote:
>[color=green]
> > For an e-commerce site, I'm wanting to have it pull 4 random images
> > for the front page from a select list of items from the DB.
> > I can get it to pull randomly and place the images, but I can't figure
> > out how to keep it from potentially repeating images; using the same
> > one more than once.[color=darkred]
> > >[/color][/color]
> I think you're missing shuffle() (and a nice clean separation of your
> presentation and logic code, but that's a different matter).
>[/color]

A "Steve" suggested I simply use "order by rand()" and limit the query
to four items, which works super simple and nice...but I'll look into
shuffle().
That may be a good solution for other issues down the line!
Plus it's always good to learn more. =)

What I'm curious about is your comment about separation and
presentation of logic code.
Since I REALLY want to be able to write clear, clean code, I was
wondering what you meant by that.
Something as simple as placing the functions all together, or more
than that?
(Because this funky function method I set up I was actually
anticipating on being temporary once I found a good solution.)
Otherwise I normally do put all my functions together.

If it's more than that, I'd certainly be interested in hearing your
suggestions!
Thanks!
Liam