多个选择语句

Question

I am trying to create a list of items in which every fourth item in the list is an item that is on from New York and On Sale. The rest of the items in the list are the items that are from New York no matter if they are on sale or not.

How can I properly use two select statements to break the list up into the order that I want? Below is what I'm using now. It creates a list of paragraphs but does not understand what the variables $article and $article2 are.

<ul>

<?
    $sort = id;
    $sql = "SELECT * FROM `Catalog` WHERE state = 'New York' and in_stock = 'yes' ORDER BY $sort";
    $result = mysql_query($sql);

    $sql2 = "SELECT * FROM `Catalog` WHERE state = 'New York' and sale_item = 'yes' ORDER BY $sort ";
    $result2 = mysql_query($sql2);

    $i = 0;

    while ( $article = mysql_fetch_array($result) || $article2 = mysql_fetch_array($result2) ) { 

        if ($i == 0) {
            echo '<li>This item number is on sale:'.article2[id]. '</li>';
                $i++;       
        } else if ($i == 3) {
                echo '<li>This item number is regular price'.article[id]. '</li>';
                $i = 0;
        } else {
            echo '<li>This item number is regular price'.article[id].'</li>';
            $i++;
        }
    }
    ?>  

</ul>

Based on Dave's suggestion I'm trying it this way. But php still doesn't know how to interpret $itemsOnSale or $items.

<ul>
<?   
$items = array();
$itemsOnSale = array();
$sql = "SELECT * FROM `Catalog` WHERE state = 'New York' AND in_stock = 'yes' ORDER BY $sort";
$result = mysql_query($sql);
while ( $row = mysql_fetch_assoc($result) ) {

    if ( $row['sale_item'] == 'yes' ) {
        $itemsOnSale[] = $row;  
    } else {
        $items[] = $row;
    }

        if ($i == 0) {
               echo '<li>This item number is on sale:'.$itemsOnSale[id]. '</li>';
               $i++;       
        } else if ($i == 3) {
             echo '<li>This item number is regular price'.$items[id]. '</li>';
             $i = 0;
        } else {
             echo '<li>This item number is regular price'.$items[id].'</li>';
             $i++;
        }

}

  ?>
</ul>

Answer 1

A better method would be to pull all items in a single query, store them in separate arrays, then reference them as necessary. In its current form your second query pulls sale items but doesn't check to see if they are in stock.

$items = array();
$itemsOnSale = array();
$sql = "SELECT * FROM `Catalog` WHERE state = 'New York' AND in_stock = 'yes' ORDER BY $sort";
$result = mysql_query($sql);
while ( $row = mysql_fetch_assoc($result) ) {
    if ( $row['sale_item'] == 'yes' ) {
        $itemsOnSale[] = $row;  
    } else {
        $items[] = $row;
    }
}

Then construct your HTML list, pulling an array item from $itemsOnSale every 4th loop.

Answer 2

It looks like you omitted the $ in front of your variable names:

echo '<li>This item number is regular price'.article[id].'</li>'; should be echo '<li>This item number is regular price'.$article[id].'</li>';

As an aside, it looks like you're trying to use what's called MARS -- Multiple Active Result Sets. Not all database drivers support this.

Answer 3

This is one of your problems:

while ( $article = mysql_fetch_array($result) || $article2 = mysql_fetch_array($result2) ) { 

If a result is found from $result , the condition will be met and $article2 never gets populated. You should re-think the flow of your while loop.

You can try something like

while ( $article = mysql_fetch_array($result) && $article2 = mysql_fetch_array($result2) ) {

but this will finish once either $article1 or $article2 is empty. However you can add another while loop afterwards with just

while( $article = mysql_fetch_array($result) ) { // keep posting regular items }

but there's a chance you may have more sale items than regular items (and everything wouldn't get posted.) There's lots of ways to do this.

Also, you have to reference variables using $ .

echo '<li>This item number is on sale:'.$article2['id']. '</li>';

You also had an extra closing bracket in your original code, check your parsing.