PHP + MySQL: When I select from two tables, how to define from which table I want to take "id"

I have two tables, each with an "id" field. Here are the two tables:

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

I have this select query:

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

Then, in PHP, I want to use id of the table news. I have this code:

while ($row = mysql_fetch_array($result)) 
{
    // I want开发者_StackOverflow 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
}

Give them aliases

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

Or

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

IN you SQL query, you can use aliases :

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

The columns will be available from PHP using the aliases, and not the names of the columns.

In your case, you'd have :

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;

And, in your PHP code, you'd use the aliases :

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

You should explicitely define the fields you want to retrieve and alias the ambigous ones:

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

user As statement in sql like

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

and in php get as

echo $row["newsid"] ;

//

echo $row["authorsid"] ;