使用PHP中的PDO在单个查询中获取行数和该行的数据 [英] Getting number of rows and data of that row in a single query using PDO in PHP

问题描述

我有一个登录系统，最初我要检查用户名/密码组合是否正确，然后获取列以设置会话变量

I have a log-in system where initially I am checking whether the username/password combination is correct and then fetching the columns to set session variables

这是我的代码

$sql='select uid,name from users where username=? and password=?';
$query=$con->prepare($sql);
$result=$query->execute(array($username,$password));
$query->setFetchMode(PDO::FETCH_ASSOC);

//check if a single row is returned 

if(($query->fetchColumn())===1)
    {
        //set session variables
        header('Location: lading_page.php');
    }
else echo "Invalid username/password";

1) fetchColumn()给出的错误结果为 3 (尽管我有与该参数匹配的单行和每行15个库仑)，而如果$sql具有曾经

1) fetchColumn() is giving wrong result as 3 (though I have single row matching that parameters and 15 coulmns per row) whereas if the $sql had been

$sql='select count(*) from users where username=? and password=?';

给出正确答案为 1 为什么?

gives correct answer as 1 Why?

2)我看到了php手册，发现rowCount()仅适用于DML查询，它建议

2) I saw the php manual and I found that rowCount() is gauranteed only for DML queries and it suggests workaround for SELECT but it costs 2 queries per login.

有没有一种方法可以使用单个查询?

Is there a way I can do using single query?

编辑

现在我正在使用类似的东西，它似乎工作正常，但问题很少.请参阅评论

Now I am using something like this and it seems to work fine but few problems .see comments

$sql='select uid,name from users where username=? and password=?';
$query=$con->prepare($sql);
$result=$query->execute(array($username,$password));

$rows= $query->fetchAll(PDO::FETCH_ASSOC);
if(count($rows)===1)
    {
          //I reached here
        echo $_SESSION['id']=$rows['uid']; //undefined index uid
        echo $_SESSION['name']=$rows['name'];//undefined index name
        //header('Location: landing_page.php');
    }
else $error="Invalid username/password";

推荐答案

希望我对此有所了解.

尝试全部提取

$rows = $query->fetchAll(PDO::FETCH_ASSOC);

以您的情况

$sql='select uid,name from users where username=? and password=?';
$query=$con->prepare($sql);
$result=$query->execute(array($username,$password));


// check if a single row is returned
// i guess to avoid the warnings you can just set the array befor like
// $row = array();
// or put @ befor the VARS in the TRUE statement

$rows = $query->fetchAll(PDO::FETCH_ASSOC));

/** 
if you have more than one result you can look at them like this

foreach ($rows as $row)
{
    echo $row['uid'];
}
**/

if((count($rows)===1)
    {
        echo $_SESSION['id']=@$rows['uid']; 
        echo $_SESSION['name']=@$rows['name'];
        // header('Location: lading_page.php');
    }
else echo "Invalid username/password";

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