MySQL按时间戳排序预先排序的记录

Question

I'm having a problem with a MySQL query. I've been following: How to select the most recent set of dated records from a mysql table and what I'm trying to do is select the most recient record and sort it by the sales_total field. So first I have to sort by max(timestamp) then sort again by sales_total. I've modified the solution offered above as follows:

$query = "(SELECT * FROM (SELECT * FROM table_name WHERE year =\'2013\' AND category=\'Network\' ORDER BY timestamp DESC) as t1 GROUP BY name) ORDER BY sales_total DESC";
$result = mysql_query($query) or die("Query failed");

This runs perfectly in PHPMyadmin, however If I try and execute the same query in a PHP script I get a Query Failed error. Anyone know why the above seems to work in PHPMyadmin but not in PHP?

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My PHP query is as follows:

$query = "(SELECT * FROM (SELECT * FROM table_name WHERE category=\'Network\' ORDER BY timestamp DESC) as t1 GROUP BY name) ORDER BY sales_total DESC";

Answer 1

Within your PHP code you have \' despite using " quotes. Also you seem to have some superfulous (and possibly error-causing) brackets. Therefore try changing your PHP query string to

$query = "SELECT * 
    FROM (
        SELECT * 
        FROM table_name 
        WHERE category='Network' 
        ORDER BY timestamp DESC
    ) as t1 
    GROUP BY name 
    ORDER BY sales_total DESC";