Question

//( ! ) Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given

不知道这个问题。请伙计们帮助我。这是我的代码：

$query = "SELECT t1.employeecode, t1.employeename, t2.v, t2.w, t3.total, t3.totals
                FROM invoice t1,salaries t2,table1 t3
                WHERE t1.employeecode = salaries.employeecode AND
                t1.employeecode = t3.employeecode
                ORDER BY t1.employeecode ASC";

    $result = mysql_query($query,$con);

    if(mysql_num_rows($result)>0){

        echo '<table><tr><th>Article title</th>&nbsp;</tr>';
        while($row=mysql_fetch_array($result)){
            //$postedon = strftime("%A %e %b %Y",strtotime($row['postedon']));
            echo '<h1><tr><td><a href="3.php?employeecode='.$row["employeecode"].'">'.$row["deparment"].'</a></td></tr></h1>';
        }

Answer 1

$ result是boolean（false）因为查询一定有问题。使用mysql_error()，

在查询中收到错误，以帮助自己

$result = mysql_query($query,$con) or die(mysql_error());

注意：Please, don't use mysql_* functions in new code。它们不再被维护and are officially deprecated。

因此请使用PDO或MySQLi（IMO PDO即可）

Answer 2

由于您将salaries表格别名为t2，因此您必须在where子句中将其引用为t2：

$query = "SELECT t1.employeecode, t1.employeename, t2.v, t2.w, t3.total,
            t3.totals
            FROM invoice t1,salaries t2,table1 t3
            WHERE t1.employeecode = t2.employeecode AND
            t2.employeecode = t3.employeecode
            ORDER BY t1.employeecode ASC";

Answer 3

似乎您的查询无效并且无法返回FALSE bool值。检查在运行时动态构建后需要检查查询的原因按照以下步骤

$ result = mysql_query（$ query）或die（$ query。“

”.mysql_error（））;

检查错误消息。似乎必须包含一些错误的列

Answer 4

尝试将工资改为t2 ..

WHERE t1.employeecode = salaries.employeecode AND

像

WHERE t1.employeecode = t2.employeecode AND

我不知道，但是我知道当我们完成给表的别名时，我们的dbms会读取该别名，而不是原生表名。

如何在一个查询中组合三个表，我需要所有行？

4 个答案: