对于每个循环PHP，插入SQL而不插入数据

Question

$student_info = array(
                'student_number'=>$_POST['student_number'],
                'student_first_name'=>$_POST['student_first_name'],
                'student_middle_name'=>$_POST['student_middle_name'],
                'student_last_name'=>$_POST['student_last_name']);

foreach($student_info as $table_row=>$information){
    $sql = "INSERT INTO student_info_db (`$table_row`) VALUES(`$information`)";

    echo $table_row . " " . $information;
}

林不是很确定为什么它不会在数据库中插入任何数据。 echo $ table_row $ information仅用于获取值并成功，但仍不插入任何数据。 问题是，怎么了？ 我很确定我在做正确的SQL ..还是我不是？

Answer 1

看来您的SQL查询字串不正确。 您正在为每个元素运行查询！ 它将每次插入数据到每一列！ 您的表中将有4个条目供一个学生信息使用！

您也不会在循环中运行查询。

您应该在循环内创建查询，然后在循环后执行查询

您需要首先从数组中查询字符串。

首先使您的查询是这样的：

尝试这样：

$student_info = array(
                'student_number'=>mysql_real_escape_string($_POST['student_number']),
                'student_first_name'=>mysql_real_escape_string($_POST['student_first_name']),
                'student_middle_name'=>mysql_real_escape_string($_POST['student_middle_name']),
                'student_last_name'=>mysql_real_escape_string($_POST['student_last_name']));

foreach($student_info as $table_row=>$information){
  $cols .= "`".$table_row."` ,";
  $vals .= "'".$information . "' ,";
  }
$cols = rtrim($cols,",");

$vals = rtrim($vals,",");

$sql = "INSERT INTO student_info_db (".$cols . ") VALUES(".$vals .")";

带有示例数据的现场演示： https : //eval.in/104428

然后您需要运行此$sql查询

像这样：

if(mysqli_query($con, $sql)
 echo "successfully inserted";
else 
 echo "something is wrong!";

Answer 2

您没有执行查询！ 首先建立与数据库的连接。 然后添加mysql_query（$ sql）来执行查询。

$student_info = array(
            'student_number'=>mysql_real_escape_string(htmlspecialchars($_POST['student_number'])),
            'student_first_name'=>mysql_real_escape_string(htmlspecialchars($_POST['student_first_name'])),
            'student_middle_name'=>mysql_real_escape_string(htmlspecialchars($_POST['student_middle_name'])),
            'student_last_name'=>mysql_real_escape_string(htmlspecialchars($_POST['student_last_name'])));

//First we need to make a connection with the database
$host='localhost'; // Host Name.
$db_user= 'root'; //User Name
$db_password= 'nopass';
$db= 'product_record'; // Database Name.
$conn=mysql_connect($host,$db_user,$db_password) or die (mysql_error());
mysql_select_db($db) or die (mysql_error());

$column = "";
$value = ""; 
foreach($student_info as $table_row=>$information){
  if($column != ""){
    $column .= ",";
    $value .= ","; 
  }

  $column .= $table_row;
  $value .= "'".$information."'";

}

$sql = "INSERT INTO student_info_db (".$column.") VALUES(".$value.")";

mysql_query($sql);  
mysql_close($conn);

Answer 3

在您的foreach循环中，运行查询。 像这样：

$student_info = array(
        'student_number'=>$student_number,
        'student_first_name'=>$student_first_name,
        'student_middle_name'=>$student_middle_name,
        'student_last_name'=>$student_last_name);

foreach($student_info as $table_row=>$information)
{
    $sql = "INSERT INTO student_info_db (`$table_row`) VALUES('".mysqli_real_escape_string($connection, $information)."')";
    mysqli_run($connection, $sql);
    echo $table_row . " " . $information;
}

此处有关mysqli_query的更多信息

Answer 4

正确的方法是使用带占位符的预备语句 ：

$sql = <<<'END'
    INSERT INTO student_info_db (
        student_number,
        student_first_name,
        student_middle_name,
        student_last_name
    ) VALUES (?, ?, ?, ?)
END;

$stmt = $dbConnection->prepare( $sql )

$stmt->bind_param( 's', $_POST['student_number'] );
$stmt->bind_param( 's', $_POST['student_first_name'] );
$stmt->bind_param( 's', $_POST['student_middle_name'] );
$stmt->bind_param( 's', $_POST['student_last_name'] );

$stmt->execute();

或者，如果您坚持使用数组作为中间阶段：

$student_info = array(
    'student_number'      => $_POST['student_number'],
    'student_first_name'  => $_POST['student_first_name'],
    'student_middle_name' => $_POST['student_middle_name'],
    'student_last_name'   => $_POST['student_last_name']
);

$keys = array_keys( $student_info );
$columns = implode( ',', $keys );
$holders = implode( ',', array_fill( 0, count($keys), '?' ) );

$sql = "INSERT INTO student_info_db ($columns) VALUES ($holders)";
$stmt = $dbConnection->prepare( $sql )

foreach ( $keys as $key ) {
    $stmt->bind_param( 's', $student_info[$key] );
}
$stmt->execute();