如何使用 MySQLi 在 PHP 中获取数据?

问题描述

我尝试了多次，但无法成功获得正确的语法——根据 PHP 5.5.12——从我的数据库中获取单行或多行.

I tried several times but cannot succeed in getting the right syntax—according to PHP 5.5.12 —to fetch single or multiple rows from my database.

session_start();
$con=mysqli_connect("localhost","root","","doortolearn");
if (!$con) {
    echo "Could not connect to DBMS";       
}
    $query="select * from teacher where tremail='$_POST[email]' and trpasssword='$_POST[password]'";
    $result=mysqli_query($con,$query);
    $flag=FALSE;
    while ($row=mysqli_fetch_array($result,MYSQLI_BOTH)) {
        $_SESSION['email']=$row['email'];
        $flag=TRUE;
    }

推荐答案

首先，$_POST[password]周围没有单引号':

First, you have no single quotes ' around $_POST[password]:

$query = "SELECT * FROM teacher WHERE tremail='". $_POST['email'] ."' and trpasssword='" . $_POST['password'] . "'";
$result = mysqli_query($con, $query) or die(mysqli_error($con));
$flag = FALSE;
while ($row = mysqli_fetch_array($result, MYSQLI_BOTH)) {
    $_SESSION['email'] = $row['email'];
    $flag = TRUE;
}

但除此之外，您是否甚至在此处设置了 MySQL 数据库连接?我看到 $con 但这真的有效吗?

But past that, do you even have a MySQL database connection set here? I see $con but is that really working?

此外，通过将 或 die(mysql_error($con)) 添加到您的 mysqli_query($con, $query) 行来检查是否存在错误.

Also, check if there are errors by adding or die(mysql_error($con)) to your mysqli_query($con, $query) line.

此外，您有一个 $_SESSION 值，但您是否在脚本的开头设置了 session_start?

Also, you have a $_SESSION value, but do you even set session_start at the beginning of your script?

但我也建议您使用 mysqli_stmt_bind_param 作为您的值，如果您不打算进行基本验证，至少可以将它们转义:

But I also recommend you use mysqli_stmt_bind_param for your values to at least escape them if you are not going to do basic validation:

$query = "SELECT * FROM teacher WHERE tremail=? and trpasssword=?";
mysqli_stmt_bind_param($query, 'ss', $_POST['email'], $_POST['password']);
$result = mysqli_query($con, $query) or die(mysqli_error($con));
$flag = FALSE;
while ($row = mysqli_fetch_array($result, MYSQLI_BOTH)) {
    $_SESSION['email'] = $row['email'];
    $flag = TRUE;
}

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