Php Opencart正在从3个表中检索数据

你好，我有这个问题：

    $sql = "SELECT email_id as name,competition_rate as rate, competition.competition_id, competition.end_date 
FROM " . DB_PREFIX . "competition_winners as competition_winners, 
     ". DB_PREFIX . "competition as competition,
    ". DB_PREFIX . "customer as customer

WHERE competition.competition_id = competition_winners.competition_id and customer.email=competition_winners.email_id";

我需要的是从表Customer中检索另一行Competition_rate。我正在使用opencart，最好将其显示在与客户电子邮件相同的行中，并将其显示为名称。它是可能的吗？它是如何实现的

p.s.稍微更改了代码，但我无法仅显示比赛或电子邮件的所有结果

  $sql = "SELECT email_id as name,customer.comptition_rate as newcomrate,competition_rate as rate, competition.competition_id, competition.end_date 
FROM " . DB_PREFIX . "competition_winners as competition_winners, 
     ". DB_PREFIX . "competition as competition,
    ". DB_PREFIX . "customer as customer WHERE competition.competition_id = competition_winners.competition_id and customer.email=competition_winners.email_id";

尝试此查询，您将获得此

newcomerate

字段上的数据

尝试以下操作：

 $sql = "SELECT email_id as name,customer.comptition_rate as rate, competition.competition_id, competition.end_date  FROM " . DB_PREFIX . "competition_winners as competition_winners, ". DB_PREFIX . "competition as competition, ". DB_PREFIX . "customer as customer WHERE competition.competition_id = competition_winners.competition_id and customer.email=competition_winners.email_id";

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祝你今天愉快

我有两个表A和B。我需要从表C中获取名称字段。我正在使用opencart。请帮帮我你的问题是这样的。我们需要所有桌子的详细资料。对不起，如果我把你和其他人都弄到了。实际上我有3个表，我只需要根据表竞争中的参数电子邮件从表c或客户字段中选择数据。\u Winner您听说过

JOIN

？您的查询和数据库结构不正确。您应该使用

JOIN

s，而不是使用

email=email\u id

作为唯一的比较键，您应该使用主键。非常感谢大家！！！它起作用了。只有瘦我做了，我添加了速率索引，以查看和控制器文件。