php错误提示：mysql_fetch_row():suppliedargumentisnotavalidMySQL

今天测试数据库连接，遍历数据表的中信息的是一直出现以下的错误：

Warning: mysql_fetch_row(): supplied argument is not a valid MySQL result resource in D:\AppServ\www\wordpress\lianjie001.php on line 20

我原来写的代码是这样的：


$db_host="localhost";
$db_database="wordpress";
$db_username="root";
$db_password="admin123";
$connection=mysql_connect($db_host,$db_username,$db_password);
mysql_query("set names 'utf8'");

$sql="select * from huanzhexinxi";
$result=mysql_query($sql);

while($resultrowzhen=mysql_fetch_row(($result))){
$huanname=$resultrowzhen[0];
$huanage=$resultrowzhen[1];
$huancall=$resultrowzhen[2];
$huanliu=$resultrowzhen[3];
echo "";
echo "名字：$huanname
";
echo "年龄：$huanage
";
echo "电话：$huancall
";
echo "患者留言：$huanliu
";
echo "
";
}


mysql_close($connection);
?>



检查半天也没有发现错误，后来经同事指点是缺少了选择数据库的代码如下所示：

$db_selecct=mysql_select_db($db_database);

完整的代码就是下面这样即可完成遍历。



$db_host="localhost";
$db_database="wordpress";
$db_username="root";
$db_password="admin123";
$connection=mysql_connect($db_host,$db_username,$db_password);
mysql_query("set names 'utf8'");
$db_selecct=mysql_select_db($db_database);
$sql="select * from huanzhexinxi";
$result=mysql_query($sql);

while($resultrowzhen=mysql_fetch_row(($result))){
$huanname=$resultrowzhen[0];
$huanage=$resultrowzhen[1];
$huancall=$resultrowzhen[2];
$huanliu=$resultrowzhen[3];
echo "";
echo "名字：$huanname
";
echo "年龄：$huanage
";
echo "电话：$huancall
";
echo "患者留言：$huanliu
";
echo "
";
}


mysql_close($connection);
?>

回复讨论(解决方案)

这到底是来提问的呢？还是来分享经验的呢？

结贴率为0，估计是一时心血来潮过来玩玩的吧

授人以鱼不如授人以渔
echo mysql_error();

mysql_query($sql) or die(mysql_error());

4楼正解.........