php pdo JOIN查询结果 [英] Php pdo result of JOIN query

问题描述

我尝试在两个都有id字段的表之间做一个简单的JOIN.我的结果是一个stdClass对象，因为我使用的是PDO.有谁知道我该如何区分第一个表的ID和第二个表的ID?

I try to do a simple JOIN between two tables, that both have the id field. My result is an stdClass object, as I use PDO. Does anyone know how can I make a difference between the id of the first table and the id of the second table?

$sql = "SELECT * FROM products AS p 
        products_categories AS c 
        WHERE c.id = p.category";

$stmt = $connection->prepare($sql);
$stmt->execute();

$products = array();

while($product = $stmt->fetchObject())
    $products[] = $product;

return $products;

如果我尝试使用$ products-> id，它将显示 category 表的ID.如果它是一个数组，我可以使用$ products ['p.id']，我需要一个替代方法.

If I try to use $products->id, it will show me the id of the category table. If it was an array, I could use $products['p.id'] , I need an alternative to this.

非常感谢.

推荐答案

您必须为一个表或另一个表的id列赋予列别名，以使列名不同.

You have to give a column alias to the id column from one table or the other to make the column names distinct.

这意味着您不能使用"SELECT *"，您必须拼写要从该表中获取的列名称​​ all .如果您希望所有这些列都没有别名，那么至少您仍然可以查询category.*.

This means you can't use "SELECT *", you have to spell out all the column names you want to fetch from that table. At least you can still query for category.* if you want all those columns without aliasing.

顺便说一句，这类问题是避免在每个表的主键中使用通用名称(例如"id")的一个很好的理由.而是使用更具描述性的名称，例如product_id和category_id.这样就不会出现列名冲突的问题.

By the way, this sort of problem is a good reason to avoid using a generic name like "id" for your primary key in every table. Instead use a more descriptive names like product_id and category_id. Then you won't have the problem of conflicting column names.

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