除非多个db_connect（）;否则SQL无法正常工作 声明

In the past I've had no issues using one simple:

$link = db_connect();

in a single file with multiple SQL commands like so:

$sql = "UPDATE table SET...";

$sql_result = mysql_query($sql, $link)
or die("Couldn't execute query.");

$sql2 = "UPDATE table2 SET...";

$sql_result2 = mysql_query($sql2, $link)
or die("Couldn't execute query.");

Now any new file I create won't work without multiple/separate db_connects. For example:

$link = db_connect();

$link2 = db_connect();

$sql = "UPDATE table SET...";

$sql_result = mysql_query($sql, $link)
or die("Couldn't execute query.");

$sql2 = "UPDATE table2 SET...";

$sql_result2 = mysql_query($sql2, $link2)
or die("Couldn't execute query.");

The old files with multiple mysql_queries referencing a single db_connect(); are still working fine. What could have changed?

Thanks.

Updated to include the db_connect(); function:

function db_connect($db="database", $host="localhost", $user="user", $p="password") {

    $dbcnx = @mysql_connect($host, $user, $p);

    if (!$dbcnx)
    {
    echo( "<p>Unable to connect to the database server at this time.</p>" );
    exit();
    }

    $database = @mysql_select_db($db, $dbcnx);
    if (!$db)
    {
    echo "<p>Unable to locate the database at this time.</p>";
    exit();
    }

return $dbcnx;
}

If you want to have $links separated, add true as fourth mysql_connect() parameter:

$dbcnx = @mysql_connect($host, $user, $p, true);

Additionally if you want to use different connections (different databases, users, passwords), you need to explicitly pass parameters to db_connect() second time:

$link2 = db_connect('database2', 'whateverthehost', 'user2', 'andhispassword');

What you have posted looks fine unless you have something unset() ing $link, assigning it a value, or something else that is making $link no longer pointing to the database.