我正在尝试从MySQL表中选择数据,但收到以下错误消息之一:
mysql_fetch_array()期望参数1为资源,给定布尔值
要么
mysqli_fetch_array()期望参数1为mysqli_result,给定布尔值
要么
在布尔值/非对象上调用成员函数fetch_array()
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'];
}
同样适用于类似
$result = mysqli_query($mysqli, 'SELECT ...');
// mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given
while( $row=mysqli_fetch_array($result) ) {
...
和
$result = $mysqli->query($mysqli, 'SELECT ...');
// Call to a member function fetch_assoc() on a non-object
while( $row=$result->fetch_assoc($result) ) {
...
和
$result = $pdo->query('SELECT ...', PDO::FETCH_ASSOC);
// Invalid argument supplied for foreach()
foreach( $result as $row ) {
...
和
$stmt = $mysqli->prepare('SELECT ...');
// Call to a member function bind_param() on a non-object
$stmt->bind_param(...);
和
$stmt = $pdo->prepare('SELECT ...');
// Call to a member function bindParam() on a non-object
$stmt->bindParam(...);
最佳答案
查询可能由于各种原因而失败,在这种情况下,mysql_ *和mysqli扩展名都将从其各自的查询函数/方法中返回false
。您需要测试该错误情况并进行相应处理。
mysql_* extension:
注意mysql_ functions are deprecated和已在php版本7中删除。
将$result
传递给mysql_fetch_array
之前,请先进行检查。您会发现它是false
,因为查询失败。有关可能的返回值和如何处理它们的建议,请参见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
程序风格:
$username = mysqli_real_escape_string($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风格:
$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 ) {
...
使用准备好的语句:
$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 ) {
...
这些示例仅说明了应该执行的操作(错误处理),而没有说明如何执行。生产代码在输出HTML时不应使用
or die
,否则它将(至少)生成无效的HTML。另外,数据库错误消息也不应显示给非管理员用户,如discloses too much information所示。关于php - mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()/mysql_num_rows等…期望参数1为资源或结果,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/40076656/