PHP + MySQL：当我从两个表中进行选择时，如何定义我要从哪个表中获取“ id”

如何解决PHP + MySQL：当我从两个表中进行选择时，如何定义我要从哪个表中获取“ id”

|| 我有两个表，每个表都有一个“ id”字段。这是两个表：

news    : id,authorid,datetime,body
authors : id,name

我有这个选择查询：

SELECT * FROM news,authors WHERE (news.authorid = authors.id) ORDER BY news.datetime DESC;

然后，在PHP中，我想使用表格新闻的ID。我有以下代码：

while ($row = MysqL_fetch_array($result)) 
{
    // I want to take news.id,but it gives an error:
    echo $row[\"news.id\"]; // error: \"Undefined index: news.id\"

    // And when I write only \"id\",it takes it of authors.
    echo $row[\"id\"]; // this id is authors.id,but I want news.id
}

    

解决方法

给他们起别名

SELECT news.id AS news_id FROM news,authors WHERE (news.author = authors.id) ORDER BY news.datetime DESC;

要么

SELECT *,news.id AS news_id FROM news,authors WHERE (news.author = authors.id) ORDER BY news.datetime DESC;

    ,在您的SQL查询中，您可以使用别名：

select table1.id as id_1,table2.id as id_2,...

可以使用别名（而不是列名）从PHP获得列。 就您而言，您将：

SELECT news.id as news_id,news.authorid,news.datetime,news.body,authors.id as author_id,authors.name
FROM news,authors 
WHERE (news.author = authors.id)
ORDER BY news.datetime DESC;

并且，在您的PHP代码中，您将使用别名：

echo $row[\"news_id\"];
echo $row[\"author_id\"];

    ,您应该明确定义要检索的字段，并为模糊的字段添加别名：

select news.id as news_id,authors.id as authors_id,authors WHERE (news.author = authors.id) 
ORDER BY news.datetime DESC authors.name

    ,像SQL中的用户作为语句

select news.id as newsid,news.authorid as newsauthorid,authors.id as authorsid ....

并在PHP中获取为

echo $row[\"newsid\"] ;

//

echo $row[\"authorsid\"] ;