这是我写的连接数据库的函数:
function db_connect(){
@$db=new mysqli("localhost","root","","trade");
if(mysqli_connect_errno()){
echo "数据库连接错误";
exit;
}
$db->query("set names 'utf8'");
//echo "连接数据库成功";
}这里是调用的代码:
43 <?php
44 db_connect();
45 $sql="select b_class,id from p_class where b_id='0' order by b_index asc";
46 $result=$db->query($sql);
47 while($row=$result->fetch_assoc()){
48 echo "<li>".$row['b_class']."</li>";这个是错误信息:
Notice: Undefined variable: db in D:\wamp\www\trade\index.php on line 46Fatal error: Call to a member function query() on a non-object in D:\wamp\www\trade\index.php on line 46这到底是咋回事呢?
function db_connect(){
@$db=new mysqli("localhost","root","","trade");
if(mysqli_connect_errno()){
echo "数据库连接错误";
exit;
}
$db->query("set names 'utf8'");
//echo "连接数据库成功";
}这里是调用的代码:
43 <?php
44 db_connect();
45 $sql="select b_class,id from p_class where b_id='0' order by b_index asc";
46 $result=$db->query($sql);
47 while($row=$result->fetch_assoc()){
48 echo "<li>".$row['b_class']."</li>";这个是错误信息:
Notice: Undefined variable: db in D:\wamp\www\trade\index.php on line 46Fatal error: Call to a member function query() on a non-object in D:\wamp\www\trade\index.php on line 46这到底是咋回事呢?
global $db;
$db=new mysqli("localhost","root","","trade");
if(mysqli_connect_errno()){
echo "数据库连接错误";
exit;
}
$db->query("set names 'utf8'");
//echo "连接数据库成功";
}这里是调用的代码:
43 <?php
$db=null;
44 db_connect();
45 $sql="select b_class,id from p_class where b_id='0' order by b_index asc";
46 $result=$db->query($sql);
47 while($row=$result->fetch_assoc()){
48 echo "<li>".$row['b_class']."</li>";
@$db=new mysqli("localhost","root","","trade");
if(mysqli_connect_errno()){
echo "数据库连接错误";
exit;
}
$db->query("set names 'utf8'");
//echo "连接数据库成功";
return $db;
}$db = db_connect();
function db_connect(){
@$db=new mysqli("localhost","root","","trade");
if(mysqli_connect_errno()){
echo "数据库连接错误";
exit;
}
$db->query("set names 'utf8'");
//echo "连接数据库成功";
}
要在外面声明下$db