警告：mysql_fetch_ *期望参数1为资源，布尔值给定错误[重复]

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

false

mysql_ *扩展名 ：

注： 该mysql_功能已被弃用，并在PHP版本7已被删除。

请先检查一下，

$result

mysql_fetch_array

false

mysql_query

$username = mysql_real_escape_string($_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扩展
程序样式 ：

$username = mysqli_real_escape_string($mysqli, $_POST['username']);$result = mysqli_query($mysqli, "SELECt * FROM Users WHERe UserName LIKE '$username'");// mysqli_query returns false if something went wrong with the queryif($result === FALSE) {     yourErrorHandler(mysqli_error($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。

ordie