php - 在 while 循环 mysql 中加入 JOIN

Question

我有这些表:

表格交易

表addonlist

表插件

我想echo addons 上的所有项目，并查看表 addons 中的 addon_id 是否与 匹配>laddon_id 来自表 addonlist 并使用给定的 transac_id 向跟踪的项目添加注释。

我有这段代码，我可以对 addonlist 中找到的项目进行注释，但它回显来自 的相同项目>插件。

    $getaddons = mysql_query("SELECT * FROM addons LIMIT 10");
    while($rows = mysql_fetch_assoc($getaddons)){
        $addonid = $rows['addon_id'];
        $addondesc = $rows['description'];
        $addonprice = $rows['price'];
        $addonstat = $rows['status'];
        $checkaddon = mysql_query("SELECT * FROM transactions t, addonlist al WHERE t.transac_id='44005' and t.transac_id=al.transac_id");
        while($rows = mysql_fetch_assoc($checkaddon)){
            $caddonid = $rows['laddon_id'];
            if(mysql_num_rows($checkaddon) and $addonid == $caddonid){
                echo "$addondesc already in your list"; // NOTE: item is already in your list
            }
        }
        echo "<strong>$addondesc </strong><button>Add to list</button>";
    }

这将显示(我的期望):

Coke 1 Litre - already in your list
Tuna Sandwich - already in your list
Hotdog Sanwich - add button
Chicken Sandwich - add button
Ham & Egg Sandwich - add button
Ham & Cheese Sandwich - add button
Grilled Cheese Burger - add button
Clubhouse Sandwich - add button
Goto - add button
Arrozcaldo - add button

但它显示的内容:

Coke 1 Litre - already in your list
Coke 1 Litre - add button `// This wouldn't be appearing`
Tuna Sandwich - already in your list
Tuna Sandwich - add button `// This wouldn't be appearing`
Hotdog Sanwich - add button
Chicken Sandwich - add button
Ham & Egg Sandwich - add button
Ham & Cheese Sandwich - add button
Grilled Cheese Burger - add button
Clubhouse Sandwich - add button
Goto - add button
Arrozcaldo - add button

编辑:

如果我的数据库结构有问题或者只是我的代码，请告诉我。

Answer 1

使用LEFT JOIN在一个查询中获取所有内容。对于不在 addonlist 中的插件，您将从 addonlist 中获得列的 NULL，并且您可以在循环中对其进行测试。

$getaddons = mysql_query("SELECT a.addon_id, a.description, a.price, a.status, l.laddon_id
                          FROM addons AS a
                          LEFT JOIN addonlist AS l ON a.addon_id = l.laddon_id AND l.transac_id = '44005'
                          LIMIT 10");
while ($rows = mysql_fetch_assoc($getaddons)) {
    $addonid = $rows['addon_id'];
    $addondesc = $rows['description'];
    $addonprice = $rows['price'];
    $addonstat = $rows['status'];
    if ($rows['laddon_id']) {
        echo "$addondesc already in your list";
    } else {
        echo "<strong>$addondesc </strong><button>Add to list</button>";
    }
}

似乎不需要加入交易，因为您没有使用该表中的任何内容。