Why is it always warning:mysql_fetch_object (): supplied argument is not a valid MySQL Resul

Why is it always

Warning:mysql_fetch_object (): supplied argument is not a valid MySQL result resource in D:\AppServ1\www\forum\index.php O N Line 46


Code:
$id = $row ["id"];
$res =mysql_query ("SELECT count (*) as total from reply where topic id= ' $id '");
$r = Mysql_fetch_object ($res);
Guys, help me.

Reply to discussion (solution)

Topic id= ' $id '//It's wrong here.

How to change it?

You put SQL statements inside MySQL to run, see if there's any results

The last $id with a hyphen, don't write it directly into SQL.

Table structure and requirements are not posted out, how to change only you know.

Topic something.

$res = mysql_query ("SELECT count (*) as total from reply where id=". $id);

Topic is another table.

Topic is another table that has to use a connection query or a multi-table compliant query

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