我试图从MySQL表中 Select 数据，但收到以下错误消息之一:
mysql_fetch_array()希望参数1是给定的资源
这是我的代码:
$username = $_POST['username'];
$password = $_POST['password'];
$result = mysql_query('SELECT * FROM Users WHERE UserName LIKE $username');
while($row = mysql_fetch_array($result)) {
echo $row['FirstName'];
}
查询可能会因各种原因而失败，在这种情况下，mysql_*和mysqli扩展都将从各自的查询函数/方法返回false.您需要测试该错误条件，并相应地进行处理.
100:
NOTE在php版本7中删除了mysql_ functions are deprecated和mysql_ functions are deprecated.
判断$result，然后将其传递给mysql_fetch_array.你会发现它是false，因为查询失败了.有关可能的返回值以及如何处理它们的建议，请参阅mysql_query文档.
$username = mysql_real_escape_string($_POST['username']);
$password = $_POST['password'];
$result = mysql_query("SELECT * FROM Users WHERE UserName LIKE '$username'");
if($result === FALSE) {
die(mysql_error()); // TODO: better error handling
}
while($row = mysql_fetch_array($result))
{
echo $row['FirstName'];
}
mysqli extension
procedural style:
$username = mysqli_real_escape_string($mysqli, $_POST['username']);
$result = mysqli_query($mysqli, "SELECT * FROM Users WHERE UserName LIKE '$username'");
// mysqli_query returns false if something went wrong with the query
if($result === FALSE) {
yourErrorHandler(mysqli_error($mysqli));
}
else {
// as of php 5.4 mysqli_result implements Traversable, so you can use it with foreach
foreach( $result as $row ) {
...
oo-style:
$username = $mysqli->escape_string($_POST['username']);
$result = $mysqli->query("SELECT * FROM Users WHERE UserName LIKE '$username'");
if($result === FALSE) {
yourErrorHandler($mysqli->error); // or $mysqli->error_list
}
else {
// as of php 5.4 mysqli_result implements Traversable, so you can use it with foreach
foreach( $result as $row ) {
...
using a prepared statement:
$stmt = $mysqli->prepare('SELECT * FROM Users WHERE UserName LIKE ?');
if ( !$stmt ) {
yourErrorHandler($mysqli->error); // or $mysqli->error_list
}
else if ( !$stmt->bind_param('s', $_POST['username']) ) {
yourErrorHandler($stmt->error); // or $stmt->error_list
}
else if ( !$stmt->execute() ) {
yourErrorHandler($stmt->error); // or $stmt->error_list
}
else {
$result = $stmt->get_result();
// as of php 5.4 mysqli_result implements Traversable, so you can use it with foreach
foreach( $result as $row ) {
...
这些例子只说明了应该做的事情(错误处理)，而不是如何做.生产代码在输出HTML时不应该使用or die，否则它(至少)会生成无效的HTML.此外，数据库错误消息不应该显示给非管理员用户，因为它是discloses too much information.